Lyon clinched the 2019 Emirates Cup with a 2-1 victory over Arsenal thanks to two goals from Moussa Dembele, with Gunners' striker Alexandre Lacazette forced to hobble off injured.
Lacazette required treatment on his ankle early on and had to come off after just 12 minutes, to be replaced by the impressive Reiss Nelson. He was later pictured in a protective boot after the match, but manager Unai Emery played down concerns.
"We are thinking it's not serious," he said. "He [Lacazette] decided with a doctor and with me that it's better to not to take a further more risk. He tried to continue playing but it was better in preseason not to take a risk. The doctor said he is going to check tomorrow but he is thinking it is not serious. He has a sprained ankle."
However, Lyon were level on 66 minutes when Dembele headed home Memphis Depay's cross.
Arsenal thought they had re-taken the lead when summer signing Gabriel Martinelli squeezed the ball home, but the Brazilian saw his effort ruled out for offside. Then Lyon broke down the other end and Dembele kept his cool to slot past Bernd Leno.
The defeat was Arsenal's first in preseason, having so far claimed victories over Colorado Rapids, Bayern Munich, Fiorentina and a draw against Real Madrid before succumbing on penalties.
They face Angers on Wednesday, and play Barcelona on Sunday in their final friendly, before starting their Premier League campaign at Newcastle.
Earlier in the day, Arsenal Women were beaten 1-0 by their Bayern Munich counterparts thanks to Melanie Leupolz's goal.