Robert Guerrero knocked down Andre Berto twice on the way to a unanimous-decision victory in a welterweight bout on Saturday.
Guerrero (31-1-1) floored the former 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. Berto failed a doping test earlier this year, wiping out a lucrative rematch with Victor Ortiz.