The 43-12 defeat from London Irish sent them bottom of the Gallagher Premiership table, but could prove even costlier for van der Merwe who was adjudged to have struck Kyle Rowe with an elbow while fending off a second-half tackle with the score poised at 24-5.
Commentators, and fans on social media were split on the decision but referee Jack Makepeace could be heard discussing a “forearm to the face” following the incident. The South African-born Scottish international could now face a further punishment with a red card automatically resulting in a further disciplinary citing.
Further penalty would certainly be a blow to Gregor Townsend’s plans. van der Merwe has played in all three games in the competition so far, scoring a try in the 17-26 defeat to France last month.