Toby Flood has been cited for an alleged "tip tackle" during the Aviva Premiership match against Worcester, the Rugby Football Union have announced.
The England fly-half will face an RFU disciplinary hearing on Tuesday and any suspension resulting from the tackle, in which Andy Goode was pitched on to the ground during Friday's match, could endanger his presence in Leicester's crucial Heineken Cup pool games against the Ospreys and Toulouse this month and cause him to miss the start of England's Six Nations campaign, against Scotland.
Problems are mounting for Wales. Injury to George North could hardly have come at a worse time. Although the neck damage he suffered during the Scarlets' 47-12 defeat at Ulster on Friday has proved not to be as serious as first feared, he remains a worry for Wales' Six Nations defence, which starts on 2 February.
Wales are on a run of seven successive defeats and already know that they will be without Rhys Priestland, the fly-half whose ruptured Achilles tendon will rule him out of the entire tournament.
Rob Howley's reign as interim head coach has been blighted by a series of injuries, many to forwards. The wing North was carried off on a stretcher after he collided with his opposite number, Andrew Trimble, whose knee caught him on the head.
In a statement, the Scarlets said that North had travelled home with his team-mates after scans revealed no serious damage. "It is too early to assess the full extent of the injury or indeed the recovery period at this stage," the club said.
North, 20, is vital to Howley's prospects of turning around Wales's form in the Six Nations. He has scored 11 tries in 26 appearances for his country, including two on his debut against South Africa in 2010.
There was some joy for Welsh rugby last night when Cardiff Blues took advantage of Munster's poor home form to register a 17-6 Pro12 victory, with Owen Williams and Robin Copeland scoring their first tries for Blues. The real joy for Howley and Wales fans was the continued progress of the young fly-half Rhys Patchell, who converted both tries and landed a penalty as part of an influential performance.
There was only suffering, though, for Newport-Gwent Dragons, who went down 30-11 at Connacht, without ever threatening to extend the home side's poor recent run.