Already accepted as one of the greatest boxers of any era, American Floyd Mayweather Jr decided to come out of retirement for a third time to add further gloss to his glittering career.

The undefeated five-division world champion has not fought for 17 months but will take on Mexico's five-time world champion Juan Manuel Marquez in a non-title welterweight bout in Las Vegas on July 18.

"I'm going to go down in history as one of the best fighters that ever lived," Mayweather, 32, told Reuters after holding a news conference with Marquez in downtown Los Angeles on Monday.

"I'm just trying to put extras on my mark in the Hall of Fame. I'm not here to rate myself. I just thank God that he blessed me with the ability that I was blessed with."

Mayweather, who has an unblemished career record of 39-0 with 25 knockouts, never expected to miss boxing as much as he did after announcing his retirement last June.

"I was really missing just being around the sport," said the American, who is nicknamed "Money" and known for his blistering hand speed and superb defence.

"I was training every day, going to the fitness gym and to the boxing gym every now and then and working on it anyway, so I said to myself I may as well take it to the next level."

Mayweather has not fought since his 10th round stoppage of Britain's Ricky Hatton in a WBC welterweight title bout in December 2007 but believes he is already in good shape.

"I've been training for the last two or three months and my camp has been going great," he said with a flashing smile.

"I could box 12 rounds right now but I want to be able to box 12 rounds at a very high speed and pace so we are going to push ourselves and eventually we will get to that point."

Mayweather was widely regarded as the world's best pound-for-pound fighter when he retired from the sport but that status has since been claimed by Manny Pacquiao.

The Filipino southpaw rocked the boxing world with a stunning second round knockout of Hatton in Las Vegas earlier this month to claim the IBO light-welterweight title.

"Pacquiao went out there and did what he had to do," Mayweather said. "Ricky Hatton didn't stick to the game plan, and any fighter can get caught cold in the first couple of rounds. So things happened but we move on.

"I don't fight for bragging rights," he added, referring to the mythical pound-for-pound tag. "I did that early in my career. This is now a whole new era of fighters. I'm just here to continue to do what I do and that's to be the best."

(Reuters via China Daily May 20, 2009)