VIDEO: Bok Bismark fights teammate
Du Plessis, never one to shy away from a good old rugby altercation, went head to head with his fellow front row forward Haouas before Montpellier's clash with Racing 92.
The Montpellier duo exchanged punches before teammates dragged them apart.
Montpellier eventually won the match 41-3.
"In the good old days, it sometimes happened like that in the locker room, it shows that it means something to the players," said former Scotland boss and current Montpellier coach Vern Cotter.
Captain Louis Picamoles added: "These are things that happen, but there's nothing nasty. We are a group that gets on well, but sometimes it boils over a little and it's settled between men."
Video Credit: Canal Rugby