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Proceed with caution: Reporters had better think twice about prodding an unusually reserved Floyd Mayweather.

Mysteries surround Mayweather-Marquez

The promoters of the Floyd Mayweather-Juan Manuel Marquez fight have dubbed it "Number One/Numero Uno," their selling point being that it pits America's No. 1 fighter, Mayweather, against Mexico's top boxer, Marquez.

They're also hyping it as the battle for the No. 1 spot on the mythical pound-for-pound list, even though Manny Pacquiao and his supporters certainly would disagree.

Mayweather-Marquez, however, might as well be called the "Mayweather Mystery Tour."

There are two mysteries surrounding the fight, which was supposed to take place Saturday but was postponed until Sept. 19 (HBO PPV) at the MGM Grand in Las Vegas because Mayweather said he suffered a rib injury.

Re-starting the promotion this week, Mayweather and Marquez, the lightweight champion who is moving up in weight, spoke to reporters on a teleconference. But rather than provide straight answers to the burning questions of the day, they were evasive, especially Mayweather, who ducked questions like he's ducked elite welterweights.

Asked repeatedly to detail his injury, Mayweather refused.

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Floyd Mayweather has refused to go into details on how he suffered a rib injury during training.

Asked yet again for a clarification on the contract weight, both fighters refused to answer, as did promoter Richard Schaefer of Golden Boy Promotions. All they would say is that it's a welterweight fight -- even though multiple sources with knowledge of the contract have told ESPN.com that the maximum weight is 144 pounds.

That makes it a welterweight fight -- anything above 140 pounds to 147 is technically a welterweight match -- but you have to wonder, why all the secrecy? They were more guarded with information than the Bush administration.

Mayweather (39-0, 25 KOs), who is coming out of retirement and hasn't fought since knocking out Ricky Hatton in a welterweight title defense in December 2007, was cryptic with the discussion of his injury.

"The rib injury, you know, it happened in training," he said. "I don't have to say much, but believe me it wasn't a small guy that did it. It didn't even come from sparring. So nobody really knows what it came from. That's it right there, I know what it came from exactly. Freak accidents happen in training. We do a lot of different workouts in training and freak accidents happen. So it was just a freak accident."

Care to elaborate?

"Well, when it happened I tried to work through it," he said. "I was fine for a while. But then it happened again. And I was like, well, you know what? I can't try to be a superhero or be Superman. It's best to take your time, take a little time off, let it heal and come back, so when I do go out and perform I'll be able to perform to the best of my ability for my fans."

Asked again if it happened while sparring or running or some other exercise, Mayweather offered only, "I would never tell exactly what happened. I just had a rib injury. But by Sept. 19 you won't be able to tell because I'm going to perform. I'm going to be at my best."

Pressed again during the call, Mayweather sounded like he was getting annoyed.

Reporter: "Why is it a secret about your rib injury? Can't you just say, 'Hey, I took a shot [in the ribs]'?"

Mayweather: "Wait, slow down. Slow down. Who said it was a secret? I got hurt in training and I'll leave it at that."

Reporter: "And how is your injury?"

Mayweather: "I don't have to go in depth about what happened to me. I got a rib injury in training and I'm healed, and now I'm ready to rock and roll."

Reporter: "You can't say whether it's from a punch or just hitting the bag, or what?"

Mayweather: "What did I just tell you?"

Although there has been healthy skepticism about the veracity of the injury, Marquez (50-4-1, 37 KOs), at least publicly, said he believed Mayweather.

"I'm sure that there's solid evidence," Marquez said through a translator. "There should be some paperwork from the doctors. And I'm sure that he presented the paperwork that was needed in order to prove that it was a legitimate injury. I was calm. I'm fine. I mean, things happen for a reason. This happened and I'm OK. I'm ready to go."

Then there is the debate about the weight. Even though some outlets reported it as a 143-pound fight and sources directly involved in the fight told ESPN.com it was 144, Mayweather isn't saying.

When asked if he would have a problem making 143 pounds, Mayweather, who estimated his weight at 149 or 150 during the call, said, "I'm not weighing 143. This is a welterweight fight. Whatever I come in weighing, that's what I come in weighing, but I don't have to weigh 143. I don't know where you heard those rumors from."

Schaefer, who won't publicly discuss the weight so as not to damage the fragile business relationship he has forged with Mayweather, added, "It will be the most covered weigh-in ever because everybody wants to know what the weight is. So make sure you don't miss it!"

Marquez, who has never been heavier than 135 pounds for a fight, toed the party line when asked about the weight.

"There is an agreement between us, and the fight's a welterweight fight," he said. "Anything over 140 pounds is considered welterweight. This is a welterweight fight and we'll see come weigh-in day."

Golden Boy boss Oscar De La Hoya followed Schaefer's lead, using the weight question as a way to hype a fight many view as a Mayweather rout.

"Everybody wants to know what the weight is," he said. "Well, I think the whole world is going to be tuning in and making an event itself on what the weight is, and you can watch Friday night [Sept. 18] on what both fighters are going to be weighing."

Mayweather-Marquez undercard

The rematch between featherweight titlist Chris John (42-0-2, 22 KOs) and Rocky Juarez (28-4-1, 20 KOs) has been tentatively rescheduled for Sept. 19 on the Mayweather-Marquez undercard.

"Both camps have agreed on the compensation, but now I need to get it approved by Team Mayweather," Golden Boy Promotions CEO Richard Schaefer told ESPN.com.

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Chris John-Rocky Juarez II will likely land on the Mayweather-Marquez undercard on Sept. 19.

Mayweather Promotions has final say on many details concerning the card, including undercard bouts. John and Juarez fought to a draw in an all-action fight in February. Although most believed John won, it was an exciting fight and a rematch was scheduled for June 27, but it was postponed a week before the fight because John was ill. However, John adviser Sampson Lewkowicz told ESPN.com that John was cleared to begin training Tuesday and he expects the bout to be finalized.

"We've agreed on everything but we have no contract yet," he said. "I say, yes, it will happen, but at the same time we haven't signed the contract. With Mayweather being the boss, you never know."

The PPV could also include a lightweight match between all-action fighter Michael Katsidis of Australia and 2004 U.S. Olympian Vicente Escobedo. It's a fight Golden Boy attempted to make earlier in the year, but Katsidis turned it down.

"Now Katsidis is willing to do it," Golden Boy matchmaker Eric Gomez told ESPN.com. "Escobedo has wanted it from the beginning."

Holding it up? "It's a money issue on both sides," Gomez said. "It's a little expensive."

Khan goes for title

England's Amir Khan came out of the 2004 Olympics with a silver medal and massive hype to go with fast hands and heavy punches. In 2007, Khan was named ESPN.com's Prospect of the Year. However, Khan's star dimmed in September 2008 when he was stunningly knocked out in the first round by Breidis Prescott, who headlines this week's "Friday Night Fights" (ESPN2, 10 p.m. ET).

Khan hooked up with trainer Freddie Roach and rebounded with two victories, including a five-round technical decision against Marco Antonio Barrera in March.

Now, the 22-year-old Khan (20-1, 15 KOs) can grab back his mantle as boxing's next big thing by capturing a world title at junior welterweight against Ukraine's Andreas Kotelnik (31-2-1, 13 KOs) Saturday night in London.

Kotelnik, 31, who is making his third defense, is irritated by talk from Khan's camp that the fight is a steppingstone for Khan to bigger fights.

"All I hear from Khan's camp is that he's going to be fighting [Ricky] Hatton or [Juan Manuel] Marquez or even King Kong after he has beaten me," Kotelnik said. "Amir thinks that all he has to do is turn up and he'll be walking away with my title. He's very arrogant for a fighter who hasn't even had a world title fight yet, and I plan on punishing him badly. I'm the one who will be going on to bigger and better things later this year because I am the one who is going to win this fight."

Khan, who is moving up from lightweight, has taken exception to some of Kotelnik's comments in which he has said Khan is too young and inexperienced to compete with him.

"If he's going around saying that I am a kid, then I will let my fists do the talking," Khan said. "He's going to be in for a shock. If he thinks it is going to be an easy fight for him, then he has got something else coming. It will be exciting, but at the end of the day it will be me with the belt around my waist, and we will see who the child is then."

Dan Rafael is the boxing writer for ESPN.com.