It was not quite what Mike Tyson had in mind but the image his words conjured up could not have been more appropriate.

"They've put a muzzle on me," he said in that soft, slightly effeminate lisp which sits so oddly with the actions of the man who was once the meanest fighter the world had ever seen.

Tyson, in fact, was talking about the advice from within his own camp to cut out the four-letter tirades which have dominated the run-up to his comeback fight. But, as Evander Holyfield's mutilated ear can testify, there are times when Tyson could do with a muzzle a little less metaphorical and a good deal more physical.

Tyson has displayed a mood of such simmering tension and rank bad humour this week that no-one could rule out a repeat of the biting incident which found him banned from boxing and cost him 18 months out of the ring.

It could, of course, have much to do with the need to sell seats for an event which has not seen customers exactly clamouring to pay between $200 and $1,200 a ticket. Organisers still hope to see a sell-out at the MGM Grand Arena and they know the smouldering aura surrounding Tyson is their best hope of keeping the cash wheels turning.

There is a lingering sense of danger, a tremor of uncertainty and a distinct feeling with Tyson, that anything is still possible.

Tyson weighed in last night at a muscled 223 pounds - the heaviest career. Botha scaled in at 233.