Harlequins lock George Robson has been charged for the head-butt that resulted in his dismissal during the 26-15 defeat by Wasps.
Robson was shown a red card just 46 seconds into Saturday's Guinness Premiership opener at Twickenham, after leaving Wasps scrum-half Joe Simpson with a bloody nose.
The Quins forward must appear before a Rugby Football Union disciplinary panel at a London hotel tomorrow night and faces a minimum four-week ban.
The top-end sanction for striking an opponent with the head is 12 weeks, but a suspension of up to two years can be issued for the offence if it is deemed serious enough.
The panel will consist of Jeremy Summers (chairman), Peter Budge and Gerard Rees.
Robson's dismissal marked an appalling start to the season for Quins, whose reputation has been left in tatters by the 'Bloodgate' scandal that has rumbled on for much of the summer.