Britain's Ricky Hatton knocked out Jose Luis Castillo of Mexico in the fourth round to retain his IBO light welterweight title in Las Vegas last weekend.

The end came two minutes 16 seconds into the round when a Hatton left hook to the ribcage caused Castillo to grimace in agony, turn away, and fall to one knee, where he remained while referee Joe Cortez counted to ten.

"He got me good," admitted Castillo to reporters.

"It was a perfect shot. I couldn't breathe. I couldn't get up."

Hatton said he was confident of victory early in the fight and was happy with the clinching combination.

"Head first, left hook, left hook, and that's what finished him," said Hatton.

"In my heart, after the first round, I felt he wasn't going to last long."

Although the end was sudden, Hatton, who remained unbeaten at 43-0 with 31 KOs, had looked the stronger fighter throughout.

He pressed forward from the opening bell, using superior footwork to find angles from which to launch left hooks to Castillo's head and body.

In contrast, Castillo, who fell to 55-8-1 with 47 KOs, sought to smother the champion and land uppercuts and body shots from close range.

He had some success with his tactics in the third round, which was the only round that any of the judges scored in his favour.

But several of his punches strayed low, earning him rebukes and ultimately a point deduction from Cortez.

It was Hatton's third consecutive fight in the United States, and he was far more satisfied with the result than he had been with his relatively pedestrian victories over Luis Collazo and Juan Urango.

"My first two fights in the US weren't my best," he said. "This was much better. I really worked hard on this performance. I felt very strong inside."

Asked about a possible clash with Floyd Mayweather Jr., widely regarded as the best fighter in the world, Hatton was dismissive of his potential future opponent.

"There was more action in those four rounds than Floyd has had in his whole career," he said.