Amir Khan is prepared to fight anyone as he continues his quest to be recognised as the next pound-for-pound king.

Khan took another step towards claiming boxing's most prestigious accolade when he became unified light-welterweight champion with a fifth-round stoppage of Zab Judah at the Mandalay Bay Events Centre.

Accusations made by veteran American southpaw Judah that the knockout blow was low - replays suggested it was legitimate - failed to take the shine off a masterful display from the 24-year-old.

Judah was viewed as dangerous opponent capable of causing an upset, but he was outboxed and bullied by his younger rival and seemed to be looking for a way out from an early stage.

It was a highly impressive display from Khan, whose stock continues to rise on this side of the Atlantic.

"I'll fight anyone and there are some big names out there for me. I'll take a look at the short list," said Khan.

"My aim is to move up the pound-for-pound rankings and to one day be pound-for-pound champion. I want to be the best fighter in the world.

"I'm still a fight or two away from there yet. At 25 I'll fight at 147 pounds and see where we go from there.

"We just keep on collecting titles, that's what we want to do. I'm only 24 and there's a lot of improvement to come."

Adding Judah's IBF title to his own WBA belt proved surprisingly easy as a fighter who had mixed it among the best of his era - including Floyd Mayweather and Kostya Tszyu - was picked apart.

Judah was fazed by the hand speed and aggression of his opponent, who marched forward with intent throughout a dominant performance.

The straight left, Judah's most dangerous shots, was hardly seen thanks to Khan's movement.

The punch stats showed Khan landed 61 times to Judah's 20 and by the fifth round he had won each session on all three of the judges' scorecards.

When the end came it was shrouded in controversy with Judah, his left eye swollen and nose bleeding, claiming he had been felled by a low blow.

Locked in a tangle, Khan spotted an opening and drove a right uppercut through the middle that landed just above the waistline of the shorts.

The American went down and was counted out by referee Vic Drakulich with 13 seconds of the round remaining, resulting in jeers from his disgruntled supporters.

Khan, however, was content he had ended the contest legitimately.

"I don't think it was a low blow. It was a clean shot and the referee was there," he said.

"In my eyes it was a clean shot, just above the belt. Zab took the shot.

"It was a very hard shot and we'd been working on the shot throughout our camp.

"It happened naturally, I fired the uppercut and it worked for me."

He added: "I felt sharp. The gameplan was to keep away from Zab's powerful back hand, so we always had to move from it and we did that well.

"Zab's very awkward, at times I was missing him and he's one of the quickest fighters I've faced.

"I still think he's got a lot in the tank, he'll still win a world title."

Judah thought Drakulich's count was to give him time to recover from the low blow and only realised his error when it was too late.

He had absorbed a barrage of punches before the crucial punch landed and the lack of passion evident when later making his case suggested that he was happy enough the fight was over.

"I don't make any excuses but that was a low shot," he said.

"I went down and the referee was counting, I figured he was counting for a low blow - the eight count to get myself together.

"But when I heard him say 'nine, 10, it's over' I said, 'what do you mean it's over, it's a low blow'.

"We'll have the right people take a look at it. But Khan fought a good fight."

The manner of victory has taken Khan closer to his dream showdown with Floyd Mayweather - pencilled in for late next year - and the Olympic silver medallist is inspired by the prospect.

"The Mayweather fight is something I'm looking at the for the future and it would be huge for me. It would drive me on," he said.

"I've got the speed and the skills and with (trainer) Freddie Roach polishing me up a little more, it's a fight we can win."