Lyon president Jean-Michel Aulas has expressed concern over next week's trip to Istanbul after crowd trouble in Thursday's Europa League quarter-final first leg against Besiktas.
Police have reported the arrest of a dozen fans from both teams, with five officers and two supporters suffering minor injuries after fighting broke out inside the Parc Olympique Lyonnais before kickoff.
The start of the game was delayed by 45 minutes as officials attempted to clear the pitch of large numbers of Lyon fans, who had attempted to shield themselves from firecrackers and other projectiles coming from the stands.
After the match, which finished 2-1 to the hosts, Aulas told French television station W9: "I hope UEFA will take all the necessary measures. It seems difficult to travel to Besiktas. When you see how this fury spilled over on all sides we are very afraid.
"With the intense fireworks, severe injuries and homemade bombs exploding around them our fans had only one option, to take refuge on the pitch. I've heard some people ask 'but how could a pitch be invaded?' Well thankfully, if they hadn't invaded the pitch, they would have been trapped by Turkish fans who had turned up in strength, some without tickets.
"I don't know what needs to be done [in the second leg], play behind closed doors or elsewhere but it will be too dangerous for us to play this match with the same fans that were here tonight."
Thursday's incidents from Lyon came during a week when the Borussia Dortmund team bus was attacked with explosives just before their Champions League game at home to AS Monaco on Tuesday.
In addition, there were clashes between Leicester City fans and Spanish police in Madrid prior to Wednesday's quarter-final first leg at Atletico Madrid.
