Violent clashes leaving one fan in a critical condition delayed Thursday's Europa Conference League game between Nice and Cologne in southern France, local authorities announced.
The match in Nice's Allianz Stadium had been due to kick off at 18:45 local time (16:45 GMT) but was pushed back to 17:40GMT, after fighting broke out in the stands between rival French and German supporters.
"UEFA and local authorities have decided to postpone the match to 7:40 p.m.," the stadium announcer said, warning that the game risked being cancelled in the case of further incidents.
Eleven fans were reported injured with a German supporter hospitalised in a "critical condition" after falling in the mayhem.
"The man fell five meters between the first and second level of the stands. The accident occurred after the incidents in the stadium," Benoît Huber, director of office of the prefect of the Alpes-Maritimes, told AFP.
"Calm has now returned," Huber added.
The two clubs are playing in the first round of Group D of the Europa League Conference, the smallest of the three European football competitions.