Julio Cesar Martinez made Moises Calleros pay in the ring Friday night for his unprofessionalism at their weigh-in Thursday.

Martinez’s speed and power was entirely too much for Calleros, who was a late replacement in their 112-pound championship match at TV Azteca Studios in Mexico City. Mexico’s Martinez (17-1, 13 KOs, 1 NC) scored a knockdown in the first round, clobbered Calleros with power shots during the second round and stopped him before that second round ended.

Referee Cesar Castanon stepped between them to stop the action at 2:42 of the second round on the Juan Francisco Estrada-Carlos Cuadras undercard. Calleros (33-10-1, 17 KOs) was still standing when Castanon halted the fight.

Calleros agreed to challenge Martinez on less than one week’s notice. Martinez had been scheduled to defend his WBC world flyweight title against another Mexican opponent, Maximino Flores, but Flores (25-4-2, 17 KOs, 2 NC) tested positive for COVID-19. The 31-year-old Calleros couldn’t win Martinez’s title because he Calleros came in 5½ pounds overweight Friday.

A left hook by Martinez knocked Calleros into the ropes 28 seconds into the second round. Martinez’s right hand knocked Calleros into the ropes 1:15 into that second round.

Calleros tried to fight back, but Martinez blasted him with a right hand that snapped his head back and knocked him into the ropes with 25 seconds to go in the second round. Martinez jumped on his vulnerable opponent and unloaded power punches until Castanon came to Calleros’ rescue.

A left-right-left combination by Martinez made Calleros go into a squatting position and use his right glove to keep himself from going down. That counted as a knockdown just 50 seconds into the first round. Martinez then knocked Calleros off balance with a left hook when there was about a minute remaining in the opening round.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.