Neymar was one of five players sent off after an injury-time brawl as Marseille beat Paris St-Germain in Ligue 1.
As he left the pitch, the Brazilian told the fourth official he had heard a racist comment.
Florian Thauvin scored the only goal as PSG lost their opening two Ligue 1 games for the first time since 1984-85.
But a late brawl saw PSG substitutes Leandro Paredes and Layvin Kurzawa, and Marseille duo Jordan Amavi and Dario Benedetto, sent off along with Neymar.
The referee watched a VAR replay of a punch from Neymar before showing him a straight red card.
After the match Neymar tweeted that his “only regret” was not hitting Alvaro Gonzalez in the face, having struck him on the back of the head.
In the post-match press conference Marseille manager Andre Villas-Boas said: “There is no place for racism in football but I don’t think that was the case… we’ll have to look at it.”
The game – which was watched by a crowd of about 5,000 fans at the Parc des Princes – was fractious even before that late brawl. There were 17 cards shown in total, a record for a Ligue 1 game in the 21st century. (BBC)