Arsenal dominated the first leg of their Europa League semifinal after Sime Vrsaljko was sent off with a second booking just 10 minutes into the game. But despite a host of chances, Arsenal were only 1-0 up through Alexandre Lacazette's second-half header when Antoine Griezmann scored a late equaliser.

It was a result that felt more like a loss for the Gunners after what had shaped up to be a great European night at the Emirates -- and also Wenger's final European home game.

"Of course you come out tonight with a bitter taste. Because we had chances to be in the final tonight," Wenger said. "And that's where the regret is. And we were not clinical enough and we gave unfortunately a goal away, which puts you in a very difficult position.

"Once we were 1-0 up, the task was clear for us: not to be caught on a long ball. Because they could not combine enough to come out and create a chance. The only chance they could have was on a long ball.

"We were a bit unlucky on the goal because it was a foul on [Danny] Welbeck. But we can only look at ourselves on tonight's results. Because 1-0 is a perfect result at home. It was just down to us after that not to make a mistake. It's a story we have seen before."

Griezmann scored after a comedy of errors by Arsenal's defenders, with Laurent Koscielny failing to hold off his fellow France international and then kicking the ball into his own face to let him run through on goal. After David Ospina saved his first effort, Shkodran Mustafi then slipped to let Griezmann hammer home the rebound.

Wenger, though, refused to blame Koscielny for the goal.

"It's not about blaming individuals. It's about the whole team is very disappointed and down," Wenger said. "So for us to have a chance to qualify [the first task] is to rebuild, get the disappointment out of the way, and rebuild the desire and confidence to go there and qualify."

The second leg is in Madrid next Thursday, and the Gunners now must score an away goal against a side that has one of the best defensive home records in Europe.