ONTARIO -- Gilroy's Robert "The Ghost" Guerrero scored a unanimous decision victory over Andre Berto to retain his WBC interim welterweight title Saturday night in front of 4,865 fans at Citizens Business Bank Arena.

Guerrero (31-1-1, 18 knockouts) dominated from the onset, pushing Berto (28-2, 22 KOs) into the ropes before uncorking three left hands that sent the 29-year-old to one knee midway through the first round.

Guerrero, 29, landed another solid left that floored Berto again in the second.

The pounding continued throughout the 12-round bout, with Berto occasionally finding space to unleash blows to Guerrero's head and body.

Guerrero was unfazed, constantly moving forward and keeping the fight with Berto's back to the ropes.

"I told Andre that I was going to beat him down, so I had to keep my word," Guerrero said. "He didn't hurt me. He's a strong guy, but I got a great chin."

All three judges scored the fight 116-110 in favor of Guerrero.

The loss was the first for Berto since dropping a unanimous decision to Victor Ortiz on April 16, 2011.

CompuBox had Guerrero landing 258 punches to Berto's 182.

Guerrero earned $1 million for the fight, his biggest payday of his career.