Neymar was sent off on his return from Covid-19 quarantine after reacting to an alleged racist slur as Marseille snapped their 20-match winless run against Paris Saint-Germain with a 1-0 victory over the reigning Ligue 1 champions on Sunday.
Florian Thauvin's close-range volley on 31 minutes earned Marseille a first victory over their bitter rivals since November 2011 but an ugly scuffle at the end resulted in five red cards at the Parc des Princes.
Neymar, in his first game since testing positive for coronavirus last week, was dismissed in injury time for a slap on Marseille defender Alvaro Gonzalez.
The Brazilian appeared to accuse his opponent of racism as he followed red-carded teammates Layvin Kurzawa and Leandro Paredes down the tunnel after he was sent off following a VAR review.
"Look at the racism. That's why I hit him," Neymar said as he left the pitch.
"The only regret I have is not hitting this idiot in the face," he tweeted after the match.
Neymar "told me it was a racist insult, but I didn't hear anything on the pitch", PSG coach Thomas Tuchel said.
"There is no place for racism in football but I don't think that was the case," Marseille coach Andre Villas Boas told Telefoot. "We'll have to look at it."
Argentine striker Dario Benedetto and left-back Jordan Amavi were shown red cards for the visitors.Marseille are attempting to close the gap on PSG after coming a distant second last season and find themselves with an early six-point advantage over a club that has won the title seven of the past eight years.
"It's an important win, it's historic. It's a very good win, a tough and obviously difficult one," said Villas-Boas.
After fielding a depleted line-up at Lens on Thursday, Tuchel was able to recall Neymar and Angel Di Maria for a match played in front of around 4,000 supporters in Paris.
However, Kylian Mbappe remained absent after testing positive for Covid-19 on France duty at the start of the week with Mauro Icardi and Marquinhos also still missing.
PSG handed a debut to Italy international Alessandro Florenzi following his arrival on a season-long loan from Roma while Sergio Rico started in goal after rejoining on a long-term deal.
Marseille 'keeper Steve Mandanda produced a magnificent reflex to keep out an effort from Marco Verratti just a minute in as tempers bubbled over frequently in the capital.
Thauvin, who shone in Marseille's opening 3-2 win at Brest before the international break, made the breakthrough when he turned in a Dimitri Payet free-kick from point-blank range.
Di Maria found the net for PSG just past the hour but had strayed clearly behind the last defender, and Marseille's celebrations were cut short in similar fashion moments later when a Benedetto goal was ruled offside.
The Argentine rifled in a rebound after Rico parried from Thauvin, who was controversially adjudged to be in an offside position much to the frustration of Marseille.
PSG's last goal came in the 3-0 win over RB Leipzig in the Champions League semi-final on August 18, and Neymar poked wide from a Pablo Sarabia cross before the contest turned ugly at the finish.
"It's a bit disappointing we ended like that," said Thauvin. "We didn't want to get into that sort of game."