ONTARIO -- Gilroy boxer Robert "The Ghost" Guerrero won't disclose much about his strategy for defending his WBC interim welterweight title Saturday night, but he does indicate HBO viewers shouldn't tune in late for his bout against Andre Berto.

"We're jumping on the Autobahn. We're going pedal to the metal, full gas from start to finish," Guerrero said of his plan to take advantage of the fact Berto might be rusty after going 14 months between fights because of a failed drug test.

For Guerrero, the bout at Citizens Business Bank Arena some 45 miles east of downtown Los Angeles is another step up the boxing ladder after he took time off in 2010 to help his wife Casey in her battle against leukemia. This will be his first million-dollar purse and, if everything falls into place, a possible steppingstone to an even bigger payday against Floyd Mayweather Jr.

But Guerrero (31-1, 18 knockouts) -- who is fighting for only the second time since going 15 months between bouts because of rotator cuff surgery -- insists he is only focused on Berto (28-1, 22 knockouts) in a pairing of ambitious 29-year-olds.

In Berto, Guerrero is facing an opponent who twice has held the WBC welterweight title and defeated Dejan Zavec on Sept. 3, 2011, in his last fight. Berto had been scheduled for a June return bout against Victor Ortiz -- who put the one blotch on Berto's record -- but that fight was canceled because of a positive steroid drug test.

Berto successfully appealed that finding to the California State Athletic Commission, which agreed the norandrosterone found was only trace contamination on a nutritional supplement.

Still, the cheater tag came up in last week's media conference call.

"It was a tough situation," Berto said. "But, me and my team, we really didn't worry too much, because we knew we didn't do anything wrong. It was just the fact of just coming out and proving that."

Guerrero hedged when asked if he considered Berto clean or a cheater.

"Who knows? Only God knows and he knows," Guerrero said. "That's the least of my concerns. My concern is to be prepared for this fight and to go do my job."

Guerrero resumed his boxing career after a bone-marrow transplant at Stanford improved his wife's health. She currently is doing well and sat ringside at his last fight, a 12-round decision over Selcuk Aydin at HP Pavilion on July 28.

"Seeing what she had to go through, it makes you step back and look at the bigger picture," Guerrero said, adding that her drive sets an example for him.

Berto's career has been touched by outside challenges as well. In 2010 he had to cancel a fight against Shane Mosley so that he could return to Haiti and assist in relief efforts after several members of his extended family were killed in a 7.0 earthquake.

Guerrero has won titles at three lower weight classes, but his fight against Aydin was his first in the 147-pound welterweight division. Berto, however, referred to Aydin as a "punching bag," noting that Guerrero is now facing someone with a much different style.

And Berto didn't sound worried that his 14-month layoff would be a problem.

"I've been having some great workouts," Berto said. "I don't think there's going to be too much ring rust."

The "interim" tag on Guerrero's title is tied to the fact Mayweather has yet to say what his plans are after serving two months last summer in a Las Vegas jail after a domestic abuse plea. Before that, Mayweather had held the welterweight title outright.