Argentina and Stade Francais fly-half Nicolas Sanchez was floored by a "punch" from Montpellier prop Gregory Fichten during a Top 14 clash.
Poor discipline from the visitors ultimately aided Stade in their 32-10 bonus-point victory on Saturday.
The pinnacle of that indiscipline was Fichten being red carded after what some have reported to be a punch.
Sanchez had been involved in a tackle with around five minutes remaining in the first half of the match when the opposing prop arrived for the clear-out, RugbyDump reports.
TV footage appears to show his forearm connecting with Sanchez's face, clearly taking the half-back by surprise as his head rocks back and he falls to the ground.
The front rower was swiftly given his marching orders.
Stade had been leading 8-3 at the time of the incident.
They then took full advantage against 14 men and cruised to a 32-10 victory in the Top 14 battle.
