Familiar failings haunt Arsenal
Arsenal had it all to do in Madrid, after a late Antoine Greizmann equaliser in the first leg gave Atlético an away goal advantage.
The north Londoners started the game well, having their fare share of possession inside the opening 20 minutes. Their first chance came when Alexandre Lacazette whipped in a dangerous cross that Danny Welbeck was unable to get on the end of. A promising start.
However, things soon turned sour for the visitors. Captain Laurent Koscielny went down under no contact after getting his studs caught in the turf. The Frenchman was stretchered off with a ruptured achilles tendon and was replaced by Calum Chambers.
The early change didn't seem to affect Arsenal, as they continued to push forward in such of an all important away goal. Héctor Bellerín and Nacho Monreal's overlapping runs were key to Arsenal's attacking structure, as Atlético had packed central areas of the pitch.
Despite seeing a lot of the ball, the Spanish full-backs were unable to have any real impact in the final third, with their crosses often blocked or overhit.
In injury time in the first half, Arsenal - not too dissimilar to the first leg - were guilty of switching off and were duly punished. Griezmann picked out Costa in acres of space with a pinpoint through ball. The former Chelsea hitman bore down on David Ospina and proceeded to lift the ball over him into the roof of the net.
There were question marks over Arsenal's defensive line, particularly aimed at Bellerín who seemed to be caught out of position. The Gunners had been sucker punched right on the brink of half time.
Atleti cruise to the finish
In seventeen La Liga home games this season, Atlético Madrid had only conceded four goals. A quite remarkable record, even for a team renowned for their defensive strength.
As the minutes in the second half ticked away, it was clear to see why so many teams failed to find a way past Diego Simeone's men.
Atlético set up in two banks of four, with centre back Diego Godín dominant in the air, dealing with any balls in the box with consummate ease.
Arsenal did have an opportunity to equalise after a set piece delivery found it's way to Aaron Ramsey, but the Welshman could only steer his effort wide.
Griezmann and Costa proved a threat at the other end of the pitch, linking up well and forcing saves from Ospina. Despite not adding to the scoreline, Atlético never seemed in danger of letting the match slip and the lack of anxiety amongst the home support was testament to that.
Wenger's last European game in charge of his beloved club had ended in defeat. Beaten by the better team over two legs, Arsenal's lack of defensive stability once again proved an obstacle.
Attention now turns to Arsenal's final three league games, although they cannot win a trophy, they will still want to finish the season strong and send long-serving boss Wenger off with a smile.