Harlequins have suspended Dave Ward for one game after the hooker was shown a yellow card for stamping on Wasps' Thomas Young at Twickenham Saturday.
Ward also appeared to spit at Young, an incident which was missed by referee Craig Maxwell-Keys but was shown on television, although the Harlequins player denied that it was intentional.
"I apologise unreservedly to Thomas Young, Wasps and everyone at Harlequins for my yellow card yesterday," Ward said.
"I would also like to make clear that I did not spit on another player during the match yesterday. Regardless of what the television footage looks like I know that I have never spat on a player in all my career and will never do so."
The Premiership club released a statement on Sunday confirming they had made the decision following a review while head coach Paul Gustard described the incident as "unnecessary and regrettable".
"We do not coach, condone or accept foul play and on behalf of the team and the club, I apologise to Thomas, Dai [Young] and Wasps for this incident," Gustard said.
"It was an unnecessary and regrettable incident in what was a tightly contested match at Twickenham."
Ward could yet face further disciplinary action if the case is brought to the RFU. If charged, the forward could face a minimum four-week ban, which could rise to as much as 12.
Despite Ward's time in the sin bin, Harlequins defeated Wasps 20-13 in what was the 11th annual "Big Game" to be played at Twickenham.