(In conjunction with HBO Sports, Yahoo! Sports will be featuring special Q&A entries from Manny Pacquiao and Timothy Bradley Jr. as they train for their showdown on June 9. This is part 2 of 4 from Pacquiao.)

What is it about Juan Manuel Marquez and his style that seems to give you trouble? Will you give him a fourth fight? Are there any options for you after this fight besides a fight with Marquez or Mayweather?

I get asked a lot about my fights with Juan Manuel Marquez. Our trilogy has been as exciting for us as it has been for boxing fans. Juan really understands how to fight southpaws. He's a very smart man and an excellent fighter. His deliberate and patient style of fighting is a product that comes from experience and experience against great opposition. He's a brilliant counterpuncher.

My trainer Freddie Roach has said many times that Juan is the only smart one out there; the only fighter who has figured me out.

Manny Pacquiao has plenty of distractions before his fight with Timothy Bradley. (Getty)

I know the fans want to see a fourth fight between us and I can understand why. Right now I can only focus on the task at hand and that's defending my title against Timothy Bradley. Just because Bradley is moving up in weight doesn't mean he is at a disadvantage, believe me I know. I've moved up in weight a few times myself. No one has ever beaten him – no one. Freddie and I have four weeks of very hard training to prepare for this fight. I cannot afford to be distracted by thinking of other fights. That is a lesson experience has taught me.

Friday, May 11
What are Bradley’s strengths in this matchup, what are your advantages, and do you have any concerns about his physical style and the frequency of head clashes in his fights?

Timothy Bradley brings a lot of weapons to a fight. He has youth, an aggressive style and a state of mind that only a world champion possesses. No matter how much talent a fighter has, his game is raised by being a world champion. Tim has always found a way to win. He has great determination and can adapt and change his game plan in mid fight.

Bradley seems to be improving with every fight. His victories over Lamont Peterson and Devon Alexander, who were undefeated when he fought them, were very impressive. He knows how to impose his will on his opponents. He turns fights into wars.

I have speed and power to counter Bradley. My experience against Hall of Fame caliber opposition is also an advantage for me. I have learned so much from fighting legends such as Oscar De La Hoya, Miguel Cotto, Erik Morales, Marco Antonio Barrera and Juan Manuel Marquez. I also have the best teacher in my trainer Freddie Roach.

I do have concerns about Bradley's fighting style. Anytime a southpaw fights an orthodox-style boxer headbutts are bound to happen, but with Bradley it's more of a concern because he tends to lead with his head. Hopefully we will have a good referee who will not let him do that. Regardless, it's my job to be prepared for anything he may bring.

Pacquiao vs. Bradley takes place Saturday, June 9 from the MGM Grand Garden Arena in Las Vegas and will be produced and distributed live by HBO Pay-Per-View beginning at 9:00 p.m. ET/ 6:00 p.m. PT.

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ALBANY, N.Y. (AP) Karim Mayfield floored Raymond Serrano at the fourth-round bell, and then landed a solid right hand less than a minute into the fifth that stopped the challenger in the NABO junior welterweight title fight Friday night.

Mayfield and Serrano both swung at the bell of the fourth round, but Mayfield's punch landed, sending Serrano (18-1) to the canvas. Serrano eventually returned to his corner, wobbling and recovering barely enough to go out for the fifth

''I stayed composed,'' Mayfield said. ''My corner told me that was a shot that was going to be hard to recover from. A minute's time wasn't long enough time to recover from a shot like that. In my mind I was thinking, I don't want to let this opportunity go where I could've gotten him out of there, but didn't.''

Mayfield (16-0-2 10 KOs) came out with a flurry in the fifth, and referee Eddie Claudio stopped it with Serrano staggering 47 seconds in.

''He fought a good fight,'' Serrano said. ''He caught me with a good shot. I'll be back.''

Mayfield, listed shorter by an inch and crouching to make himself shorter, effectively ducked under many of Serrano's punches in the first three rounds. Mayfield sent Serrano down in the third with a right counter and two more punches.

''I'm only 5-7, maybe even giving myself two inches,'' Mayfield said. ''When you got a guy that's shorter than you and a guy goes down lower, it's a little timid, because you don't want to be reaching down to jab. Coming up with that coiling style is very intimidating, because you have to reach down, and I'm actually reaching up while you're reaching down. I knew I could make opportunities from that.''

Serrano was game, especially starting out.

''I was surprised how easy it was for me to hit him,'' Serrano said. ''He's strong.''

''He's a pit bull,'' Mayfield said.

But Mayfield crouched and kept his distance in the opening two rounds and was able to counter in the third. He nearly ended it with his right hand at the bell to end the fourth.

''Honestly, I was hoping he was a little timid - but he wasn't,'' Mayfield said. ''I caught him with a great shot that put him down. That normally should've put a lot of guys out. He shouldn't have gotten up from that, because I caught him flush.''

In the junior middleweight undercard, Kevin Rooney Jr. lost for the second time, beaten by late replacement Anthony Jones in a four-round decision. The southpaw Jones, who also fought and won four rounds nine days ago, came out aggressively and barely let up. Jones knocked Rooney down twice - in the first round and solidly with a straight left in the second. Rooney landed two good rights in the third round, including an overhand right, but it wasn't enough. Rooney falls to 4-2.

LOS ANGELES (AP) Former welterweight champion Andre Berto has failed a doping test, and the promoter of his rematch with Victor Ortiz says next month's fight is off.

Berto denied using steroids Friday, but said he couldn't explain the voluntary test that showed evidence of nandrolone usage.

Golden Boy Promotions CEO Richard Schaefer said Berto tested positive last weekend, and a secondary test also came back positive Friday. Berto and Ortiz are scheduled to fight June 23 at Staples Center in Los Angeles, but Berto will be replaced by a new opponent for Ortiz.

''Obviously it's unfortunate, but at least it will allow us to save the event,'' Schaefer said, praising Berto adviser Al Haymon for promptly informing Golden Boy of the positive test. ''Victor will be fighting, and all the other fights on the card will happen. We will be announcing within the next two days the replacement (for Berto).''

The fighters agreed to doping tests for their rematch through the Voluntary Anti-Doping Association, a Las Vegas-based organization that tests blood and urine for steroid use and other banned substances.

Berto (28-1, 22 KOs) said he has only received a one-page summary of the laboratory's findings, and he plans to ask for complete laboratory documentation of the testing.

''At the present time, I cannot explain the positive drug test, which was provided as part of a voluntary anti-doping program in which I agreed to participate,'' Berto said in a statement. ''I know that I have never used any steroids or other banned substances, and I am investigating all possible causes of the positive test with my attorney Howard Jacobs. I have never cheated, and all of my success has come from hard work and dedication.''

Berto held the WBC welterweight title for nearly three years until Ortiz handed Berto his first career defeat in a thrilling unanimous-decision victory in April 2011. Their rematch was among the most anticipated fights of the summer after being postponed from Feb. 11 when Berto tore a muscle in his left arm during training.

Ortiz (29-3-2, 22 KOs) used his victory over Berto to land a big-money bout with Floyd Mayweather Jr., who stopped him in the fourth round last September. Berto stopped Jan Zaveck to win the IBF welterweight title, which he vacated to fight Ortiz.

The test is another setback for Golden Boy, which has lost two lucrative fights in the past two months over positive tests by its fighters' opponents. Two-belt 140-pound champion Lamont Peterson was discovered to have high levels of synthetic testosterone in March, scrapping his rematch with Golden Boy's Amir Khan scheduled for Saturday in Las Vegas.

''It's a costly situation,'' Schaefer said. ''But if, at the end of the day, the result is that we have a cleaner sport, it's a price I'm willing to pay.''

Victor Conte, the founder and president of BALCO Laboratories, worked in Berto's camp for the fight. He took to Twitter on Friday to defend the fighter, saying he believes the positive test resulted from contamination.

''Anybody who believes an elite athlete would use nandrolone with an intent to cheat is uninformed,'' Conte tweeted. ''Clearly contamination in Berto case ... Because it stays in your system from (minimum) 6-18 months.''

Schaefer has criticized Peterson's camp for delaying its revelation of the fighter's positive test, forcing Golden Boy to scrap its entire fight card at the Mandalay Bay Events Center. Berto immediately made his results known to Golden Boy, allowing the Staples Center card to go on with attractive undercard fights including 140-pounder Lucas Matthysse against Humberto Soto, along with heavyweight contender Chris Arreola's next fight.

''What we need to do is we need to give Mr. Berto an opportunity to explain himself on how it happened and why it happened and what was going on,'' Schaefer said. ''What it shows is there's clearly a need for more sophisticated testing in the sport of boxing, and we at Golden Boy are happy to be shoulder by shoulder with Floyd Mayweather, who has pushed for a clean sport.''

A lot of rivals are laughing at Golden Boy Promotions chief executive officer Richard Schaefer. For the second time in a matter of weeks, a Golden Boy-promoted show is at risk after a fighter failed a random drug test.

On Friday, it was Andre Berto, who was supposed to meet Victor Ortiz on June 23 at the Staples Center in Los Angeles in a rematch of what had been one of 2011's greatest fights.

Last month, it was super lightweight Lamont Peterson who tested positive for synthetic testosterone. That test failure ultimately forced the cancellation of his Saturday title bout with Amir Khan.

This, though, is far more than a Golden Boy problem. It's a problem that plagues not only boxing, not only mixed martial arts, but sports across the spectrum.

And so, those who are laughing at Schaefer's plight may find themselves in his shoes in the near future.

Andre Berto's highly anticipated fight with Victor Ortiz is now in question. (Getty)Berto tested positive for a metabolite of the anabolic steroid nandrolone. What makes his case unique is that not only was Berto the one who requested the Olympic-style blood-and-urine testing regimen, but he used Victor Conte as a nutritionist.

Conte served a three-month prison stint in 2005 for his role in the notorious Bay Area Laboratory Co-Operative (BALCO) scandal.

Conte had been operating as something of a white hat in recent years, speaking out on anti-doping issues as a way, he said, of making amends for a mistake he made in his life.

It was hard, though, not to question Conte when Berto's urine turned up dirty. Conte immediately took to Twitter on Friday and insisted that most positive tests for Nandrolone come as a result of contamination.

He released a statement via e-mail in which he denied providing Berto with anything illegal. He had been a consultant for and a very vocal public advocate of the Voluntary Anti-Doping Association founded by Dr. Margaret Goodman. VADA ran the testing for both the Khan-Peterson fight and the Berto-Ortiz II fight.

"I had absolutely nothing to do Andre Berto's positive drug test for nandrolone," Conte wrote. "Andre enrolled in the VADA drug testing program in early 2012. While using my nutritional products and protocols, Andre's blood and urine were randomly tested twice before his recent biceps injury and all tests were negative. After his positive test was revealed, Andre admitted that he recently took some supplements that were not provided by me and did so without my knowledge. It is possible that one these supplements was contaminated with trace amounts of nandrolone and caused his positive test result."

[Also: Freddie Roach's role with U.S. Olympic boxing team a mystery]

Conte went on to say that because nandrolone is the longest-lasting anabolic steroid, "… it is unlikely that any elite athlete would use it in an attempt to cheat."

Berto's lawyer is Howard Jacobs, a noted expert in anti-doping matters who has successfully argued contamination cases after nandrolone tests in court.

In a telephone interview with Yahoo! Sports, Jacobs said he hadn't received the full laboratory report detailing Berto's failed test. He also declined to say which lab conducted the test.

"I have had a number of athletes who have been able to prove through independent testing that their vitamins or supplements were contaminated with nandrolone or nandrolone precursors," Jacobs said. "A number of those athletes ultimately pursued the supplement companies in civil litigation. [Nandrolone] is one of the more common substances that we would historically find in the supplement contamination cases."

Guillermo Coria, an Argentine professional tennis player, made a settlement with a multivitamin manufacturer in 2007 after the sides agreed that Coria's positive test result was because of a contaminated vitamin.

A jury awarded swimmer Kicker Vencill $500,000 in 2005 after he proved a multivitamin he took was contaminated by a steroids precursor. A judge vacated the jury's award and Vencill and Ultimate Nutrition, the drug manufacturer, reached a confidential settlement.

[Also: ESPN's First Take hosts miss mark with 'apology']

Contamination happens, without question. But so does flat-out cheating. And that's a problem that all those who make a living from the fight game have to work together to solve.

It sounds melodramatic to say that one could die at the hands of an athlete chemically enhanced by performance-enhancing drugs, but superstar fighter Floyd Mayweather Jr. said earlier this month it's why he won't fight anyone who doesn't agree to the testing.

"When my career is over, anything can happen and my health is more important than anything," Mayweather said prior to his May 5 bout in Las Vegas with Miguel Cotto. "I'm not saying nobody is, or nobody is not doing it. But my health is more important than anything. Guess what? When my career is over, if I'm hurt, or something is going on, because something has happened in a fight, I can't come to you and say, 'Yo, I need you to pay my rent for this month. I need you to pay my bills for this month. I need you to pay my car note. I need you to put my kids through school.' So, my health is more important."

It's a health problem and a financial one. Schaefer estimated Golden Boy would lose more than $250,000 after having been forced to cancel the Khan-Peterson show. He said Friday he plans to go forward with the June 23 card and would find a new opponent for Ortiz, but there is no one out there who could make for remotely the same kind of bout on such short notice.

On Friday, all of his rivals were laughing at Schaefer.

A warning to all those who took joy in Schaefer's plight: Be prepared. One day soon, it will happen to you.

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LOS ANGELES (AP) Manny Pacquiao says he loves and supports gays and lesbians, even though he does not approve of gay marriage.

The world champion boxer and Filipino congressman has been criticized ever since he was quoted in an interview on the examiner.com website saying he opposed President Barack Obama's support for gay marriage.

Pacquiao said Wednesday in an interview with The Associated Press that he doesn't support gay marriage because of his Roman Catholic beliefs. But he said he has gay friends and relatives, and supports their rights.

''I'm not against the gay people,'' Pacquiao said. ''I'm not condemning them. ... I have a cousin (who is) gay. I have relatives (who are) gay. I have a lot of friends (who are) gay, so I'm not condemning gays. What I said is I'm not in favor of same-sex marriage. That's the one thing I said to the guy.

''I told (the reporter) I'm against same-sex marriage,'' Pacquiao added. ''He said, 'Why?' I said, 'It's the law of God.' That's all I said.''

The examiner.com story contained a Bible passage from Leviticus calling for the death of ''a man (who) lies with a man,'' and Pacquiao said many readers erroneously believed he had quoted that verse.

He said he had not, and the writer later clarified in a follow-up post that he had included the verse himself.

''My favorite verse in the Bible is 'Love one another,' and 'Love your neighbor as you love yourself,''' Pacquiao said. ''It's in the Bible: Do not judge. I'm not judging.''

Pacquiao was banned from a popular Hollywood shopping mall after the article was publicized Tuesday, and an online petition encouraging sponsor Nike to drop Pacquiao received 4,868 signatures before it was suspended Wednesday morning. The petition site, change.org, posted a note saying that the author of the original article had clarified that Pacquiao didn't cite the Bible passage.

Pacquiao spoke to the AP next to his pool at his comfortable Los Angeles home, where the congressman lives while training for fights at Freddie Roach's Wild Card Gym in Hollywood. The champion had the day off from training, spending the morning in medical exams before a big lunch and some relaxation.

Although Pacquiao is experiencing a newfound passion for his religion and has socially conservative views in line with many Filipinos' beliefs, he was eager to clear his name after a 24-hour avalanche of criticism over the belief that the eight-division world champion boxer had denounced gay rights and even supported the killing of gay people.

Although he opposes same-sex marriage, Pacquiao declined to weigh in on civil unions, the internationally popular alternative, saying he didn't know enough about the concept to form an opinion.

''It's hard to give a correct answer to what's the right situation,'' he said.

The expansive Los Angeles mall known as The Grove, where the syndicated entertainment-news show ''Extra'' films its episodes, wouldn't allow Pacquiao to film a segment on its premises, worrying that an appearance by the boxer could be disruptive. Host Mario Lopez, an avid boxing fan, instead filmed an interview with Pacquiao at the fighter's home.

Pacquiao chuckled at the knowledge that his words - even words he said he didn't say - carry more weight than those of an average athlete because of his political aspirations.

''With great power comes great responsibility, so that's my responsibility, to handle everything,'' Pacquiao said. ''This has happened before. You have to explain and understand. It's a lot more fun to train (for a fight).''

Pacquiao is the Philippines' most famous person and one of the world's most popular athletes. The eight-division world champion is a movie star, singer, pitchman and congressman, representing the Sarangani province in the Philippines' House of Representatives since May 2010.

He has won 16 consecutive fights since March 2005, beating Oscar De La Hoya, Juan Manuel Marquez, Miguel Cotto, Shane Mosley and Antonio Margarito. He will defend his WBO welterweight title against Timothy Bradley on June 9 in Las Vegas.

Pacquiao has embraced Catholicism in recent months after marital trouble with his wife, Jinkee. Although he has always attended Mass before his fights, the boxer has taken up frequent Bible study, and he traveled from the Philippines to the U.S. in the company of a spiritual adviser and pastor, Jeric Soriano, now a regular presence in Pacquiao's life in Los Angeles and the Philippines.

''It's difficult sometimes, but God gave me a talent,'' Pacquiao said. ''He gave me a wisdom and a knowledge.''

Although Pacquiao has some conservative social views, he also has ties to progressive American politicians, including Nevada Sen. Harry Reid. The boxer campaigned for the Democratic majority leader during his tough re-election victory over Sharron Angle in 2010.

Pacquiao also visited Obama at the White House last year, discussing basketball and boxing. The fighter says he enjoyed meeting Obama, but didn't share his views on same-sex marriage.

Pacquiao is the fourth of six children born into poverty in the Philippines, and he has four children of his own with his wife. He has spoken out against birth control during his political career, affirming his Roman Catholic faith.

Floyd Mayweather Jr., Pacquiao's only rival for pound-for-pound supremacy in boxing, took to Twitter on Wednesday to tout his own beliefs.

''I stand behind President Obama & support gay marriage,'' Mayweather tweeted. ''I'm an American citizen & I believe people should live their life the way they want.''