Robert Guerrero remains unfazed on the eve of the biggest fight of his career

Robert Guerrero says the pressure is on Floyd Mayweather ahead of Saturday's fight at the MGM Grand in Las Vegas.

Mayweather puts his unbeaten record on the line against the 'Ghost' in his first fight since his incarceration last June on a battery charge.

The Michigan native will be looking to extend his 43-0 record but Guerrero insists he is not fazed by taking on the best pound-for-pound fighter on the planet.

"The pressure's on him to stay undefeated and keep his legacy," said the Californian. "He signed a big contract and he's got a lot of stuff to fulfil. I've dealt with losses and come back so it's not on me, it's on him.

"My focus is on what I've got to do to get the job done in the ring, executing my gameplan and doing what I have to do."

Guerrero jumped up two weight classes in a direct attempt to earn a clash with Mayweather having failed to get the big fights he craved as a world champion in three lower divisions.

And the 30-year-old said the ploy paid off after securing the biggest fight out there.

"I stayed on it, kept making the fights I needed to make it happen and here it is," he said. "After beating (Andre) Berto it was like 'we gotta make this happen.'

"The first time he said he hadn't heard of Robert Guerrero it made me laugh because he wouldn't be the best fighter in the world if he didn't know who was who."