Irishman Andy Lee failed to claim the WBC middleweight title on Saturday night as he was halted in the seventh round by Julio Cesar Chavez Jr.
Chavez was hampered by leg cramps throughout the fight in Texas but was still too strong for Lee, who was rescued by the referee after he was badly hurt by a barrage from the champion.
Both men swapped big punches as the fight warmed up in the fourth, but the Mexican appeared to possess superior power as his body shots troubled Lee in the fifth.
Lee, who is based in Detroit, defiantly tried to stand and trade but his resistance was broken in the seventh as Chavez piled on the punches and referee Laurence Cole stepped in.
"I would have knocked him out earlier if it wasn't for my legs," said the still-unbeaten Chavez. "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."
Reflecting on the second defeat of his career, Lee said: "My punches had no effect on him. He just walked through them. No excuses. He's a good fighter."