Mexican Antonio Margarito retained his World Boxing Organisation welterweight title by stopping Argentina's Sebastian Lujan in the 10th round.
The bout in Atlantic City was stopped after the ring-side doctor noticed that Lujan's left ear had been torn open.
Margarito's win sets up a fight against the unbeaten American Kermit Cintron, which is scheduled for 23 April.
Margarito said: "Cintron must be good but I've met a lot of undefeated guys, and they all went home with a defeat."