Amir Khan comes of age as he retains his world title in epic encounter

Amir Khan's trainer, Freddie Roach, declared the British boxer will be good enough to beat Floyd Mayweather after he grew "from a boy to a man" during Saturday's world title defence.

Khan had to come through some heavy punishment in the late rounds to beat Marcos Maidana on a unanimous points decision to retain the WBA light-welterweight title defence in Las Vegas.

The 24-year-old was taken to hospital for a precautionary scan after a fight in which he answered critics who had questioned his chin. Roach does not believe Khan would fight Manny Pacquiao given he trains both men, but he tipped a future showdown with Mayweather.

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"It was a great fight," said Roach. "He showed a lot of heart and a good chin. He went from a boy to a man today. It was his ultimate test so far. He fought the toughest guy out there.

"I don't think him and Pacquiao will fight each other, they are very good friends. I wouldn't like to see two guys who are very friendly fight each other. Business is business and you never know but I hope Mayweather comes to the table first. I have two guys I believe who can beat him."

Roach wants Khan to face WBO light-welterweight champion Tim Bradley or Devon Alexander, who fight next month, before moving up a weight to face Mayweather.

"We need another fight at 140lb to make sure he looks good and stop making the mistakes he made," said Roach. "It could happen. If he cleans up the 140lb division and goes to 147, Mayweather won't fight Pacquiao but maybe he will fight Amir Khan.

Khan floored Maidana in the first round with a powerful body punch but he was fortunate to survive the tenth round after the Argentinian unleashed a flurry of concussive punches. But Khan would not be beaten and he negotiated the final three rounds to close out a 114-111, 114-111, 113-112.

Former British world champion Naseem Hamed said: "He boxed brilliantly in regards to coming through a very hard fight. I don't wish upon him any more bouts like that. Fights like that shorten your career.

"He must have a heart as big as a bucket of gold. To get past that tenth round to the 12. I don't know how he did it.

"I should be in the best of moods because he was victorious but the fact is I saw a close friend in there go through some tough times and I don't want to ever see that again."

Hamed believes Kahn's victory confirms him as the best 140lb boxer in the world. "He is already a brilliant fighter. He had one blip on his career (with the defeat to Breidis Prescott), he paid the price and has came back unbelievably," said Hamed."He has gone to Vegas and pulled out the performance of his life against a really tough guy, a guy who is a very concussive puncher. He is right up there with the very best. He has been man enough to pick out the hardest puncher and main fighter in his division - can't we say he is the best in his division?"

Oscar De La Hoya also believes Khan is ready to star in some blockbusting bouts in 2011 after proclaiming the fight against Maidana as the "fight of the decade".

Asked for his reaction to the show-stopping action by Sky Box Office, Khan's American promoter De La Hoya was unequivocal in his response.

"Unbelievable," he said. "Amir Khan proved not only that he has a good chin but that he's the best 140-pounder in the world, no doubt about it."