Anthony Joshua defeated Carlos Takam via a 10th round stoppage to retain his WBA and IBF world heavyweight titles.
Takam surprisingly held his ground against Joshua, despite only knowing about the fight 12 days ago.
But in a key fourth round in which both men enjoyed success, Joshua dropped his man with a hook and badly damaged the eye of his rival.
Takam was twice inspected by ringside medics but battled on until he was overwhelmed in the 10th, when referee Phil Edwards stepped in to end the contest, much to the challenger’s frustration.
Takam, 36, was under pressure but not out on his feet and some inside the Cardiff venue booed the stoppage.
“I come to fight, I don’t sit on the edge and make decisions,” Joshua said of the decision. “It was a good fight until the ref stopped it, so I have the utmost respect for Takam.
“I have no interest in what is going on with the officials, that’s not my job. I think people want to see Takam unconscious on the floor, and that’s what I was trying to get to.”
“I had to keep my cool,” added Joshua, confirming his broken nose. “I’ve got a few months to heal it up. I’ll go and see some good doctors to crack it back in place.
“If I showed any signs of weakness, the ref could have jumped in. That’s what he (Takam) tried to do, but the ref stopped it.”
Takam said: “I want a rematch, I made my preparations with 12 days to fight Anthony. I want to box him again. I want him, he is a great champion.”
With the victory, Joshua keeps hope alive that WBC champion Deontay Wilder and WBO king Joseph Parker could share a ring with him in 2018.