Arsenal's Europa League hopes suffered a serious setback after a 3-1 first-leg loss at Stade Rennes in round of 16 action on Thursday.
The Gunners took early control of the game at Roazhon Park when Alex Iwobi scored in the third minute, a curling cross-shot that bounced off the far post and into the net.
But things began to turn sour for Arsenal afterward. Benjamin Bourigeaud's equalised things for the Ligue 1 hosts in the 38th minute. Three minutes later, Arsenal went down a player when Sokratis Papastathopoulos sent off on a red card.
Rennes took the lead on Nacho Monreal's own goal in the 65th minute and Ismaila Sarr's specatucular header off a left-wing cross two minutes from full-time secured Rennes the deserved win.
"The first 40 minutes I think we controlled, we scored and we didn't concede good chances to them. But after this red card, it's different," Arsenal coach Unai Emery said in a post-match news conference. "Two yellow cards and it's the referee's decision. After, I think we must learn to play -- when it's coming like today -- with one less player on the pitch.
"Not a good experience today, because we couldn't do our work in difficult moments, in difficult minutes, with one less player, like we wanted. I think we can do better."
Arsenal had never lost to French opposition away from home in 12 previous European games.
"I think the biggest disappointment is the third goal because at 2-1, you go home and you know that there's a result where you've scored away at home and you can overcome it.," Arsenal goalkeeper Petr Czech said. "We can still overcome a two-goal deficit because in the end the goal we scored might play a big part, but we made it a little bit harder for ourselves."
The return leg is on March 14 at Emirates Stadium.