Arsenal wasted a golden opportunity to put themselves on course for the Europa League final after conceding a devastating late equaliser against 10-man Atletico Madrid in the first leg of their semi-final clash.
The Gunners led through Alexandre Lacazette and were in command against a Spanish side playing with 10 men from the 10th minute.
But the defensive frailties that have all too often held Arsene Wenger’s side back in recent years again came back to haunt them, as Antoine Griezmann handed the visitors an away goal and the advantage heading into next week’s second leg.
Arsenal came out of the traps quickly, with Lacazette hitting the post from a arching Danny Welbeck cross, before the Frenchman saw a glancing header pawed away by Jan Oblak.
But those misses were anything but the main talking point in an opening 12 minutes where Atletico saw fullback Sime Vrsaljko sent off for two yellow cards and Simeone sent to the stands for his continued protests at referee Clement Turpin.
Croatian international Vrsaljko was initially booked for bringing down Jack Wilshere in the second minute, before a late lunge caught Lacazette on the angle eight minutes later saw him dismissed.
Within two minutes Simeone followed his defender down the tunnel, the Argentine’s animated and vociferous protestations too much for the French officiating team; it’s not the first time the Argentine has seen and then been shown red, nor is it likely to be the last.
With Atleti unwilling to engage outside their own defensive third when not in possession, the Gunners domination continued and chances piled up but they found Oblak in obdurate mood the Slovenian No.1 holding a tame Wilshere header before making an impressive stop, sprawling at the feet of Danny Welbeck.
Laurent Koscielny sliced wide when he should have done better, before Nacho Montreal attempted his best Marcelo impression, only to fire his volley the wrong side of the post.
However, while the floodgates looked primed to burst open, the defensive dam constructed by Diego Godin and his cohorts somehow held firm.
And just after the half hour mark, it was the Spanish side who came closest to taking the lead; Antoine Griezmann, having warmed the hands of David Ospina moments before, fired goalwards after a strong run into the area from Thomas Partey, only to see Ospina make a fine diving save.
Atletico, even with 10 men, were showing why they have proven so hard to beat for all but the best in Europe in recent years, the hard-headed side built in the image of its manager stubbornly refusing to shift, even as Arsenal clocked up possession and continued their advances.
Indeed, frustration looked to be setting in until Lacazette’s goal just after the hour mark, owing in part to a man he will hope to partner at the World Cup this summer, Griezmann.
In his own right-back position the forward lost out when trying to flick the ball through the legs of Monreal. Two passes later, Wilshere was at the byline, standing up a cross to the back post onto which Lacazette pounced, rising above Lucas Hernandez to head past the despairing dive of Oblak.
The hosts were in the ascendency and Atletico looked, if not happy, then ready to settle for a 1-0 defeat, shown when assistant manager German Burgos brought on Stefan Savic, the defender, for Angel Correa.
Then, Arsenal did an Arsenal.
A nothing ball down the right. Nacho Monreal didn’t keep the defensive line and kept Griezmann onside. Still, Laurent Koscielny was able to get goal side of his compatriot, only he messed up his attempted overhead clearance, and stumbled; Ospina denied Griezmann, but the No.7 picked up on the rebound and forced it home, despite Shkodran Mustafi’s best efforts.
It wasn’t how Wenger will have wanted his final European home match to end. However, it was rather fitting.