Lyon boss Bruno Genesio admitted it was worrying to see crowd trouble mar their 2-1 Europa League quarter-final first-leg win over Beskitas.
Crowd disturbances at Parc OL saw projectiles thrown, fans spill onto the pitch and kick-off delayed by 45 minutes.
Once the game finally got under way, Ryan Babel gave the Turkish side a first-half lead.
However, Lyon responded dramatically late on, with Corentin Tolisso equalising seven minutes from time before veteran Jeremy Morel nabbed the winner.
“It is distressing to see such incidents,” Genesio said of the off-field drama. “This is the reverse of what should happen.
“We are here to give pleasure to people and not to see that. You had to stay focused.”
Besiktas took the lead when former Liverpool winger Babel smashed Talisca’s pass into the net in the 15th minute.
Diminutive midfielder Mathieu Valbuena tried to force Lyon back into the tie with a headed effort on the half-hour mark but, just before the break, Marcelo went even closer to scoring.
Again the Brazilian’s aim was off – he had done enough, however, to unsettle Lyon over the interval.
The siege resumed following the restart, this time with Talisca throwing himself at Oguzhan Ozyakup’s corner and nodding wide from six yards out.
Lyon boss Genesio’s response was to make a double substitution, with Christophe Jallet adding experience and young Ivorian striker Maxwel Cornet offering the element of surprise up front.
The switch helped the hosts gain territory and in the 55th minute Lucas Tousart was able to find enough space to volley into Fabricio’s gloves.
Tolisso hit a post with a header as Lyon poured forward and Cornet looked better poised to score in the 81st minute, only for Spanish stopper Fabricio to flick his attempt to safety.
The dam broke moments later. Valbuena capped his committed performance with a pinpoint free-kick to Tolisso, who stuck the ball away with a minimum of fuss.
Before Besiktas had time to react, it was 2-1, with 33-year-old defender Morel exploiting a rick from Fabricio to steal possession and roll the ball home unopposed.
Speaking about the result, the 50-year-old Genesio urged his players not to get carried away ahead of the second leg.
“We dominated in the first period, with a goal conceded from a set-piece,” he added. “We were higher after the break and we were worried about our opponent.
“It’s good to come back and win the match against a very good team.
“It’s only half-time in this quarter-final. We will have to go to Istanbul with all our weapons, all our qualities.”