AMIR Khan took just 75 seconds to fire back at his critics by seizing his fifth professional win in double-quick fashion in Nottingham.

The Olympic silver medallist hammered outclassed opponent Vitali Martynov to the canvas where he was stopped by referee Terry O'Connor despite clambering gamely to his feet.

The win enabled Khan to emphatically prove a point having been stung by recent criticism over the manner of his four previous professional victories.

Luminaries such as former world featherweight champion Barry McGuigan had cautioned the Olympic silver medallist against his habit of carrying his hands low.

But Khan vowed not to change his exhilarating style which had made him the hottest young prospect in the British game and marked him out as a potential future world champion.

And he shrugged off suggestions Martynov could be the man to test him by landing a cracking left hook to end the contest in style.

What was supposed to be a significant stamina test as he moved up to the six-round distance for the first time against a better standard of opponent turned into a rout.

And that was more due to Khan's true talent than any mismatched opponent with Martynov travelling to Britain boasting an admirable record of 10 wins from 11 paid contests.

Khan had insisted beforehand he would not go looking for his opponent early and instead try to get some valuable ring time under his belt.

But he vowed to be ruthless when the moment arrived - and that looked likely to be sooner rather than later as Martynov jigged nervously from foot to foot during the introductions.

In fact Martynov looked much more nervous during the pre-fight introductions than referee Terry O'Connor, who was happily singing during Khan's trademark Road to Amarillo' ring walk.

Khan came straight out of his corner to land a peach of a left hook on his opponent who looked much too open to last long faced with the favourite's blurring fists.

Failing to adopt any form of defence, the Belorussian was leaving himself terribly open to further punishment and it was no surprise when a neat right cued up the sweeping left hand to finish and bring another Khan contest to a premature end.

"I went in there feeling 100% just to box, hoping for six rounds but it finished early," Khan said.

"I knew he would come forward and every time he did I hit him.

"I'm not really disappointed (at the early finish). I went in there and did my job - I don't get paid overtime.

"I feel stronger, I've been training on my strength and fitness, doing weights at Bolton Wanderers and I'm feeling stronger.

"It's been hard training for this fight so I'm a bit upset that it finished in the first round. But it's good for my record. I would have loved to have shown more of myself but that's the way the fight went."