Workhorse southpaw Robert Guerrero insists he's more than just a live underdog heading into Saturday's WBC welterweight championship fight in Las Vegas with Floyd Mayweather Jr.

The problem is few outside of his Northern California hometown seem to believe him.

Only four of 32 media members polled by Showtime and its public relations affiliates sided with the challenger heading into the 147-pound fight, which will headline a four-bout pay-per-view card to be broadcast from the MGM Grand at 9 p.m. ET.

The weigh-in is Friday at 6 p.m. ET and will be broadcast live on Showtime.

"Guerrero is no slouch as he proved against Andre Berto, but Mayweather is no Berto," said Tim Smith, columnist for the New York Daily News. "Mayweather is one of the best boxers and most skilled defensive boxers of this generation. He won't be standing in one spot for Guerrero to tee off on him.

"Everyone thinks they have a plan against Mayweather, but he is so adaptive in the ring that plans unravel and boxers are left grasping at straws just to stay in the ring with him. I don't think Guerrero is the tactical match for Mayweather."

The oddsmakers concur with the writers, and most are making the champion a 6-to-1 to 9-to-1 favorite to retain his crown against Guerrero, who's 31-1-1 as a pro since 2001 and 2-0 in his new weight class after previously winning title belts at both 126 and 130 pounds.

Mayweather, meanwhile, is 43-0 overall and has belts at five weights.

Oh, and he's 20-0 in title fights compared to Guerrero's paltry by comparison 6-0.

Nonetheless, the challenger remains unconvinced.

"That oh has to go. Records are made to be broken," Guerrero said. "That record is going to be broken. He's going to have his first loss. You better believe that because I'm ready to go. I can't wait. You guys talk about (Las Vegas) being Floyd Mayweather's home, we're doing a home invasion."

The tough words are but the latest in a series for Guerrero, 30, a devout Christian and recent 700 Club guest who'd been considered among the softest-spoken commodities in the sport before ramping up the chatter to lure Mayweather, now 36, into the ring.

His co-manager, Luis De Cubas Jr., conceded that a change of heart was deemed necessary as the team grew frustrated by what they claimed was an inability to get the opponents they most coveted.

"No one wanted to fight him. You're as good as the opportunities you get." De Cubas said. "He wasn't able to get those opportunities because he was too good for his own good. So I said, 'You gotta start being a little more open. You gotta start calling guys out.'"

And to get the bigger fights, he had to hunt the bigger game.

Guerrero last fought at 130 pounds in August 2009, won four straight fights at 135 through April 2011, then leapt to 147 in 2012 and toppled previously unbeaten contender Selcuk Aydin and former title-holder Berto by wide unanimous decisions.

His 5-foot-8 frame appears lean at the new weight, but he's not stopped an opponent before the final bell since 2010. Mayweather, who also stands 5-foot-8 and has a two-inch edge in reach (72 to 70), has competed at 147 or heavier since 2006 and is 9-0, with stoppage wins over Sharmba Mitchell (TKO 6), Ricky Hatton (TKO 10) and Victor Ortiz (KO 4).

And while Guerrero's lone official loss came via split decision at 126 pounds in 2005 and was avenged by TKO six months later, another scorecard defeat – on a Mayweather undercard to Orlando Salido in 2006 -- was changed to a no-contest when Salido failed a drug test.

The loss originally cost Guerrero his IBF featherweight crown, but the title was declared vacant following Salido's test result and Guerrero won it back three months later against Spend Abazi.

Mayweather has seized upon the blemishes with a familiar refrain, insisting "There is no blueprint to beat Floyd Mayweather, but there is a blueprint to beat Robert Guerrero."

Still, Guerrero and Co. maintain they can crack the code with persistence.

"People say you need to have an A, B and C game plan, but with Floyd you need an A to Z game plan," he said. "You've got to be ready for whatever because Floyd is the type of guy that makes adjustments here and there and he makes it tough for fighters to get in there with him. You've got to be ready to make those adjustments; we've been practicing a lot of stuff.

"You've got to go in there and fight an intelligent fight with Floyd. He is a very sharp guy, a very smart guy in the ring. That is why he is 43-0. It's about being smart, using your head in the ring and maintaining your game plan."