Alexandre Lacazette’s opener put Arsenal on course for a vital win only for a comedy of defensive errors to allow Antoine Griezmann to fire home a late equaliser, and crucially an away goal.
Having played against 10 men for over 80 minutes following Sime Vrsaljko’s early dismissal; the Gunners carved out a host of opportunities to take a convincing lead into Thursday’s second leg.
But the wasteful Gunners now head into next week’s second leg in Madrid knowing they must score to have any chance of reaching the final in Lyon next month – a daunting task given Atletico have not conceded at the Wanda Metropolitano since January 20.
‘I think looking at the performance it was the worst possible result for us. We have to go there in a positive mood and qualify,’ Wenger said.
‘We can only look at ourselves. You don’t look at the stats but the performance and we know we can score anywhere, let’s focus on that but recover first and see what we can do over there.
‘We have to go over there with absolute belief that we can do it.
‘We gave away a goal from nowhere and have to overcome the disappointment. I think we could already be qualified tonight.
‘It didn’t happen, their goalkeeper made many saves and you see that they have the quality up front to take advantage of a mistake.’
Wenger also believes his side were on the wrong side of a refereeing decision in the build up to Griezmann’s leveller, Danny Welbeck appeared to be fouled just moments before the Frenchman’s effort.
The Gunners boss added:
‘I think it was a foul on Welbeck. Did the referee over compensate for the early sending off? Yes, it is possible.’