Early in the 11th, Ortiz stalked Perez toward a corner and staggered him with a right uppercut and left to the head. Perez remained motionless and seemingly out on his feet when referee Jorge Ortiz stepped in between both fighters and stopped the junior-bantamweight bout 24 seconds into the round.
Ortiz, from Mexico, has won two consecutive bouts since losing his 108-pound title to Brian Viloria in 2005 and also falling in a title fight against Ulises Solis in 2006.
Ortiz (26-6-1, 17 KOs) pressured the taller Perez from the opening rounds and was effective at scoring lead lefts to Perez's head. Ortiz also landed overhand rights to his opponents head.
But the bout also featured repeated clinches and warnings from Jorge Ortiz when both fighters landed several shots below the belt.
Ortiz enjoyed a strong seventh round as he landed left hooks and rights to Perez's head. Ortiz maintained the attack throughout the round, keeping Perez on the defensive.
Perez (12-2) recovered with strong eighth and ninth rounds as he landed effectively with rights to Ortiz's head. Late in the ninth, the action intensified with Ortiz and Perez trading combinations to the head at a furious pace.
Ortiz won the WBC 108-pound title with a seventh-round TKO over Jose Antonio Aguirre in March 2005, but was stopped in one round by Viloria in his first defense six months later.
Ortiz and Perez both weighed in at 115 pounds.
