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Robert Guerrero, right, and Andre Berto trade punches in the fourth round of a WBC interim welterweight title fight in Ontario, Calif., Saturday, Nov. 24, 2012.
ONTARIO, Calif.—Robert Guerrero knocked down Andre Berto twice on the way to a unanimous-decision victory in a welterweight bout on Saturday night.

Guerrero (31-1-1) floored the former 147-pound champion in the first round and again in the second round before persevering through a physically punishing bout.

Berto (28-2) recovered from a slow start to test Guerrero despite a closed right eye from the middle rounds onward. Guerrero's right eye also closed late in the fight, but the Gilroy, Calif., fighter hung on for his eighth consecutive win.

All three judges at Citizens Bank Business Arena scored the bout 116-110 for Guerrero.

Berto complained about the officiating after the fight, his second loss in three outings.

Robert Guerrero raises his arm after the final round of a WBC interim welterweight title fight against Andre Berto in Ontario, Calif., Saturday, Nov. 24,
Robert Guerrero raises his arm after the final round of a WBC interim welterweight title fight against Andre Berto in Ontario, Calif., Saturday, Nov. 24, 2012. Guerrero won by unanimous decision. ((AP Photo/Jae C. Hong))
Berto failed a doping test earlier this year, wiping out a lucrative rematch with Victor Ortiz.

Robert Guerrero, left, takes a punch from Andre Berto in the 12th round of a WBC interim welterweight title fight in Ontario, Calif., Saturday, Nov. 24,
Robert Guerrero, left, takes a punch from Andre Berto in the 12th round of a WBC interim welterweight title fight in Ontario, Calif., Saturday, Nov. 24, 2012. Guerrero won by unanimous decision after the 12th round. ((AP Photo/Jae C. Hong))

Robert Guerrero, right, knocks down Andre Berto in the second round of a WBC interim welterweight title fight in Ontario, Calif., Saturday, Nov. 24, 2012.
Robert Guerrero, right, knocks down Andre Berto in the second round of a WBC interim welterweight title fight in Ontario, Calif., Saturday, Nov. 24, 2012. Guerrero won by unanimous decision after the 12th round. ((AP Photo/Jae C. Hong))

Andre Berto walks to his corner after the 11th round of a WBC interim welterweight title fight with Robert Guerrero, in Ontario, Calif., Saturday, Nov. 24,
Andre Berto walks to his corner after the 11th round of a WBC interim welterweight title fight with Robert Guerrero, in Ontario, Calif., Saturday, Nov. 24, 2012. Guerrero won by unanimous decision after the 12th round. ((AP Photo/Jae C. Hong))