Floyd Mayweather, Jr. is 5-1 favourite to add Carlos Baldomir's World Boxing Council welterweight title to his collection of championship belts in Las Vegas on Saturday night.

But although the unbeaten Mayweather is widely regarded as the best pound-for-pound boxer in the world, the unheralded Baldomir is in confident mood.

"Nobody has ever expected me to win, and that's fine. But on November 4, I will show not only why I won the belt but why I will leave the ring with it," he told reporters on Thursday.

Although Baldomir has nine losses on his ledger, his record is misleading. Born into poverty in Santa Fe, Argentina, he turned to boxing in 1993 to earn extra cash to support his wife and four daughters.

Since, he says, dedicating himself to his training, he has gone undefeated in 21 bouts since 1998.

Largely unknown to fight fans outside his native Argentina before this year, Baldomir burst into the spotlight in January when he upset heavily favoured Zab Judah to take the WBC welterweight crown. He knocked out Arturo Gatti in July to retain his title.

LARGEST OPPONENT

Baldomir is the largest opponent Mayweather has faced. A natural welterweight, he reportedly weighs up to 180 pounds between bouts.

Mayweather, in contrast, won his first world title in 1998 at super featherweight, or 130 pounds; his fight with Baldomir will be only the third time he has fought at the welterweight limit of 147 pounds.

"It's a natural 180 pounder against a natural 130 pounder," promoter Dan Goossen told Reuters. "That's a big difference."

But Mayweather, who points out that he is actually slightly taller than his opponent, thinks the weight difference will work to his advantage.

"He was bigger than me when we began the media tour," he said, "but not now. He's probably not happy, having to kill himself to make weight the last couple of days. I'll bet he can't even eat anything right now. Me, I feel tremendous."

Nor is Mayweather concerned that he has had to prepare for this contest without his uncle and trainer, Roger, who is serving a six-month jail sentence for assault.

"Everything Roger's taught me is still there," he said. "After 20 years, I know what to do."

"I don't think the preparation's going to be any different," said Goossen. "I think he'll survive that. The real question is, if Baldomir's prediction of wearing Floyd down comes to fruition, then in that precious one-minute break between rounds, will a different voice in his corner be able to tell Floyd what needs to be done to turn things around?"