Italy's Sebastian Negri has apologised after his tackle left England flanker Jack Willis facing the prospect of a long spell on the sidelines.

The Wasps back row, who moments earlier had scored the fifth of his team's six tries, cried out in pain and was driven from the field on a medical cart.

Willis, 24, is having scans to assess the extent of the damage to his knee.

It appeared Negri used a move known as a 'crocodile roll' - a sometimes controversial method of clearing out players from a ruck.

It is not illegal as long as it does not involve a tackle around the neck, and no action was taken against Negri.

"A quick message to Jack Willis. So sorry about what happened yesterday," Negri said on Twitter.

"Just horrible and never nice to see. Myself and all the @Federugby boys are wishing you all the best.

"I hope to see you back on the field again soon. Take care and we all know you will be back stronger."

Willis, the current Premiership player of the season, broke into the England team last autumn having battled back from previous knee and ankle issues.

"It's one of those, it's quite emotional," said Wasps head coach Lee Blackett.

"We have seen Jack, for the last few years, come back from his last one, just on the verge of England, then gets himself in this time, and it looked a nasty one. We'll know more come today [Sunday]."