Mexico's unbeaten Julio Cesar Chavez Jnr stopped Irish southpaw Andy Lee in the seventh round on Saturday to keep his World Boxing Council middleweight title and win his 23rd fight in a row.
Referee Laurence Cole stopped the bout at 2:21 of the seventh round as Chavez, nagged by leg cramps throughout the fight, inflicted a pounding to the head and body of Lee with no punches being thrown in response.
"I would have knocked him out earlier if it wasn't for my legs," Chavez said. "From the first round my legs were bothering me. It was cramps. That's why I was standing up so straight. But I got the victory."
Chavez, 26, improved to 46-0 and one drawn with his 33rd victory inside the distance while 2004 Olympian Lee, 28, fell to 28-2 and saw his four-year, 13-fight win streak snapped in his first world title fight.
"My punches had no effect on him. He just walked through them," Lee said. "No excuses. He's a good fighter."
Most of the crowd at Sun Bowl stadium, just across the US border from his homeland, backed Chavez, a ring legend's son who is making his own fame.
"I'm very happy to carry the name and I'm forcing myself to make history in the world of boxing," Chavez said. "Every day I'm doing better."
Chavez and Lee exchanged flurries of hard punches in the fourth round and Chavez stung the Irishman with body blows in the fifth, Lee unafraid to take the power punches of the champion but taking the worse of the punishment.
"I wanted to see if he had any power. I saw he didn't have anything so I came on," Chavez said. "In the first round maybe I was a little cold. I stuck my face out there but he couldn't hurt me."
Lee tried in vain to make Chavez chase him around the ring but admitted: "It was hard to move him with my shots."
Late in the seventh round, Chavez unleashed a flurry of punches to the head and body that left Lee doubled over with his back against the ring. The Mexican continued the pounding until Cole stepped between them to end the bout.
Chavez made the third defense of his first world title, won last June when he edged previously undefeated German Sebastian Zbik by majority decision.
Chavez stopped American Peter Manfredo in the fifth round last November and took a unanimous decision over Mexico's Marco Antonio Rubio in February.