Northern Bulls lock Wilhelm Steenkamp was given a two-week Super 15 ban Tuesday for striking an opponent with his head.
The South African will miss a crucial last-round league fixture against Western Stormers in Cape Town Saturday.
And if the table toppers lose and finish only third on the combined standings, he would be ruled out of a play-off the following weekend.
A judicial hearing convened by organisers SANZAR found Steenkamp guilty of striking Costal Sharks fly-half Butch James.
The lock escaped unpunished at the time while James was later sin binned and subsequently banned for four weeks over a separate incident.
Used off the bench for much of the season, Steenkamp has become a key figure since first-choice Juandre Kruger left for France.