Marseille’s Ligue 1 home match with Lyon was postponed after visiting boss Fabio Grosso was injured when his team’s coach was attacked on the way to the ground.
Images on social media showed a bloodied Grosso laid on a stretcher.
According to AFP, the Lyon coach was hit by rocks on its way to Stade Velodrome.
The game between bottom-of-the table Lyon and 10th-placed Marseille was due to kick off at 19:45 GMT on Sunday.
Thousands of fans were already inside the ground when the announcement was made that the game had been postponed.
“We took into account Lyon’s desires for the match not to take place,” said match referee Francois Letexier at a news conference.
“Based on Lyon’s wishes and the protocol, the decision was taken not to start the match,” he added, adding that reports “have been forwarded to the relevant authorities who will decide what action to take”.
AFP reported a Lyon club source as saying Grosso, the former Italy defender, was experiencing dizzy spells.
French football expert Julien Laurens, writing on X, described it as a “terrible image for French football”.
“What a scandalous mess,” he added. “This is not the first time this has happened (and not the last sadly) but I have no words for this. Unacceptable again.”
Seven-time champions Lyon last won Ligue 1 in 2007-08. Grosso, 45, was appointed as their managed in September after former France centre-back Laurent Blanc was sacked.