LONDON -- Three thoughts from the Emirates on Arsenal's 1-1 draw with Atletico Madrid in the first leg of their Europa League semifinal.
1. Griezmann punishes wasteful Arsenal at the Emirates
Arsene Wenger's hopes of ending his reign as Arsenal manager by winning the Europa League have been left in the balance after Antoine Griezmann earned a semifinal first-leg draw for 10-man Atletico Madrid at the Emirates.
Atleti, reduced to 10 men after just 10 minutes following two bookable offences by Sime Vrsaljko, spent the majority of this tie on the back foot, with Arsenal creating a series of chances to kill the tie and book a place in next month's final in Lyon.
But with just eight minutes left to play, Griezmann cancelled out Alexandre Lacazette's headed opener with a breakaway goal following typically bad defending by the home side.
With Arsenal pushing forward for a second, Griezmann beat Laurent Koscielny to the ball and then scored from close range, with Shkodran Mustafi slipping at the crucial moment as the French forward shot at goal.
Arsenal must now score in Spain next week to have any hope of avoiding elimination on the away-goals rule, but Wenger's players only have themselves to blame for the situation they now find themselves in ahead of the second leg.
The absence of the cup-tied Pierre-Emerick Aubameyang was telling for Arsenal, with Lacazette, Danny Welbeck and Nacho Monreal all missing clear chances and Atleti goalkeeper Jan Oblak also producing at least two crucial saves.
Lacazette's goal on 61 minutes gave Arsenal the breakthrough and opened up the prospect of further damage against a tiring Atleti, who also had coach Diego Simeone sent to the stands early in the first half.
But with their defensive frailties never far away, Arsenal gifted Atletico an equaliser and now face a daunting challenge in the brand-new Wanda Metropolitano.
Arsenal are still the only the club in English football not to secure a point away from home in 2018, but they must buck that trend by getting something from their trip to Madrid next week.
2. Costa's fitness could determine tie
This would have been the perfect game for Diego Costa had the Atletico Madrid man been fully fit, rather than only being able to take his place on the substitutes' bench.
With Atleti forced to play with 10 men for 80 minutes due to the sending off of Vrsaljko for two yellow cards for late challenges on Jack Wilshere and Lacazette, the absence of Costa seriously hurt Simeone's team.
The former Chelsea forward, sidelined for almost a month with a hamstring injury, proved himself to be a master of his art at Stamford Bridge as one of those priceless centre-forwards who does not give the opposition defence a moment's peace.
With Costa playing up-front in a 10-man team, Atletico would have had a reliable outlet to give them a chance to break away and relieve the pressure on their own defenders.
Arsenal will be more than happy that Costa was not fit to face them at the Emirates, but if he is fit to start next week, Wenger's team know they will face a huge challenge in Madrid to make it to the Europa League final.
Costa and Griezmann will get chances in the Wanda Metropolitano, and Arsenal will be fortunate if they miss as many as the likes of Lacazette and Welbeck did here.
And with Griezmann scoring a crucial away goal to equalise late in the game, Costa's availability could make all the difference next Thursday.
3. Arsenal fans have forgotten how to support their team
It started well enough at the Emirates, with the stadium full for the first time in several weeks and unusually noisy too.
But the fractured relationship between the club and the fans that Wenger referred to at the weekend following the announcement of his impending departure as manager was evident as the tension grew during this semifinal first leg.
In many ways, Arsenal fans have forgotten how to support their team.
They have spent so long arguing between themselves over whether Wenger should stay or go that the players on the pitch have become an afterthought.
And there were moments in this game when the frustrations became obvious, with exasperation from the stands hinting at the unhappiness among the supporters.
With Atletico riding their luck as Arsenal missed a host of first-half chances, the home fans should have turned up the volume and backed their team, as Liverpool's supporters did at Anfield during Tuesday's 5-2 Champions League win against Roma.
But too often, it was groans of annoyance at players for missing chances, and there was precious little recognition of Wenger from the supporters.
This was a night for the Emirates to roar Arsenal to victory, but the stadium lacked the unity required for that.
Yes, the atmosphere lifted after Lacazette's opener, but Arsenal needed the noise before that.
Even though Wenger has confirmed that he is going, the sense around the Emirates during this game was that the negativity is still bubbling under the surface and will explode if Arsenal fail to make it to the Europa League final and Wenger's reign ends unsuccessfully.