Julian Savea signed a two-year deal with Toulon, joining the team following the conclusion of the Super Rugby season.
Toulon's defeat was marred by a fracas which saw a brother of one of the players run on to the pitch to get involved, confronting Savea.
Stade flanker Sekou Malacou clashed with All Black World Cup-winning wing, sparking a brawl involving virtually every player on the pitch.
Both players were eventually yellow carded but not before the France international's brother got involved.
He ran on to the pitch holding a flag in the pink colours of Stade. With his brother in the middle of the huge brawl he was not able to get at Savea - though he may have thought twice seeing the size of some of the players close up.
After being ushered off the pitch he then flared up in rage again, holding off a steward before angrily pointing a flag in the direction of Savea.
The incident had echoes of when former France No 8 Imanol Harinordoquy's dad ran on to the pitch to defend his son in a fight during a Biarritz v Bayonne clash in 2011.
The defeat left Toulon in 12th on the Top 14 standings with one win from their opening four games.
- With Daily Mail