An instant after the bell rang ending the 1st round, Tyson knocked down Norris with a left to the head. Norris got up, but said he couldn't continue because of the knee injury.

``He just hit me after the bell,'' Norris said. ``I just went down the wrong way on my right knee.''

But Tyson saw it differently. ``He walked back to corner, that shows how twisted his knee was,'' Tyson said. ``He must have twisted it getting on the stool.''

Norris was taken to Valley Hospital Medical Centre and an MRI exam showed he dislocated his kneecap, Dr Flip Homansky, a Nevada State Athletic Commission physician, said yesterday.

``The MRI clearly shows the path his kneecap took when he went to the ground,'' Homansky said. ``When he stood up, it popped back in. There's no way he could have continued. He very well mightneed surgery.''

A tape of the fight will be reviewed today, and the commission will hold a hearing on Thursday or Friday, said Marc Ratner, the commission's executive secretary.

The five commissioners have the authority to change the no-contest to a disqualification if they are convinced the late punch was flagrant. But indications are the no-contest ruling will stand.