Enzo Maccarinelli made light work of Rich LaMontagne to defend his WBU cruiserweight title for a sixth time.
The Welshman set the tone for the fight with a couple of solid left hooks in the opening exchanges and twice floored the American before the bell.
LaMontagne, 35, took further punishment in rounds two and three as the champion displayed his superior speed and power.
And after one minute and four seconds of round four, the referee stopped the fight as Maccarinelli landed at will.
Maccarinelli, fighting in front of a partisan crowd in Bridgend, said he was surprised by the ease of his victory.
"I knew he was a tough guy," he said. "I hurt him in the first round obviously.
"I could have gone in there blasting him out, but I've seen his fights before when he's been hurt and come back.
"I took my time and kept my hands nice and high.
"I neglected the jab a little bit, but he was throwing right hands and leaving himself open so I knew it was just a matter of time."
Maccarinelli said he is now ready to challenge Sheffield's Johnny Nelson for his WBO title.
On the undercard, Wales' Commonwealth Games gold medallist Jamie Arthur was stopped with a cut eye in the third round of his bout with London-based Haider Ali.