Australia loose forward Michael Hooper was cited on Monday for charging into a ruck shoulder first during the 33-13 Rugby World Cup victory over England at the weekend.
The flanker was penalised for the incident, which took place just before halftime in Saturday's Twickenham clash, but escaped further sanction from referee Romain Poite.
If found guilty of the offence of "charging into a ruck or maul without use of the arms or grasping the player", Hooper could miss Australia's Pool A decider against Wales on Saturday.
That would be a blow to the Wallabies, who have used Hooper and his fellow openside flanker David Pocock to great effect in victories over New Zealand, Fiji and England this season.
Saturday's match back at Twickenham will decide which of the countries tops the pool, with the losers likely to face twice world champions South Africa in the quarter-finals.
Last weekend's showdown with the hosts, which resulted in England exiting a World Cup at the pool stage for the first time, featured some big hits from both teams.
England flyhalf Owen Farrell was shown a yellow card nine minutes from time for a dangerous tackle on Matt Giteau but Poite decided only to issue a warning to centre Sam Burgess for a neck-high tackle on Hooper in the same passage of play.
Rugby league convert Burgess was further sanctioned on Monday when he received a "citing commissioners warning" for the dangerous tackle.
Samoa captain Ofisa Treviranus received a similar warning for "striking an opponent" during his country's defeat to Japan on Saturday.
The warnings are the equivalent of an on-field yellow card but both players will be available for their country's final pool matches.
