Paris - Former France international Sebastien Chabal faces a lengthy ban for throwing a hefty punch during his club Lyon's second division game against Agen last weekend.
The bearded back-row forward was on Thursday summoned to appear before the French national league of rugby's disciplinary commission on January 3.
If guilty he could be suspended for between two weeks and one year over the incident which has become a popular YouTube hit.
Chabal found himself in hot water after striking Agen's Marc Giraud who was holding onto his shirt in the game last Saturday.
The force of the blow knocked Giraud unconscious.
Chabal picked up a yellow card for the strike which he later described as "regrettable but a reflex action".
The 36-year-old, an iconic figure in the French game, earned 62 international caps between 2000 and 2011.