The stage is set for the two heavyweights of European football to punch, at least to their weight. Both Atletico Madrid and Arsenal have failed to live up to the lofty expectations of their fans from across the globe.
The former failed to keep pace with the runaway leaders Barcelona and the latter were let down by unprecedented uncertainty, even by their standards. Yes, we speak of Arsene Wenger stepping down as manager at the end of the season. Yeah, that happened.
With both sides having failed to mount a serious challenge in any cup competition in their respective countries as well, all eyes associated with the two clubs will be firmly on the Emirates tonight.
Here are three factors that could affect the outcome of the tie:
#3 Atletico's paradoxical defensive record this season
The side from Madrid have built their reputation firmly on the foundation of their impressive defensive record. Under Diego Simeone, the Rojiblancos have become one of the most water-tight defences going around in world football.
It is a record that is reflected by their performances at home this season. Following the goalless draw with Real Betis in their last League fixture, Atletico have now gone 11 consecutive games without conceding a goal at the Wanda Metropolitano.
What the Spanish side hasn't been able to reconcile with their imperious home record is the one they have when they travel.
Atletico have failed to keep a clean sheet in their last 8 games on the trot away from home. Even with one of the most talented men with gloves in world football at the moment in Jan Oblak in their ranks, they have struggled to replicate their defensive performances at home on the road.
What could decide the tie is which Atletico Madrid decides to show up. And with two legs in the semi-finals, we could get to witness the two extremes of their contrasting defensive displays.
#2 Battle between Mesut Ozil and Antoine Griezmann
Antoine Griezamann has undoubtedly been on the biggest assets for Atletico Madrid ever since he moved from Sociedad in 2014. Similarly, the German in the Arsenal ranks is now their undisputed main man, ever since a certain Chilean decided to switch allegiances.
They have both often been the difference for their respective sides but have also come under fire for going missing in the big games. Criticism of Ozil, for being more engaged with the national side rather than the club, has always been prevalent even among the Emirates faithful.
However, it is undeniable that when the World Cup winner turns up in the red and white for Arsenal, few can keep up with his creative genius. Antoine is among a select few who have tried and done more than a decent job.
There is one major gap in the Frenchman's resume though. He has never won a single major trophy with the club, despite coming agonizingly close twice in the finals of Europe's most elite competition.
On the other hand, Ozil has won the biggest prize in the world of football as well as La Liga title with Atletico's sworn enemies, to add to the three FA Cups he has won with the North Londoners.
The experience of the big games seems to be heavily in favor the Arsenal man, but the form and capability to find the back of the net tips the scale back in favor of the Frenchman.
Who is able to weave their magic on the night and to what extent will be a major factor in deciding the fate of the two teams.
#1 The Arsene Wenger effect
Two weeks ago, following the crushing defeat at St. James Park against Newcastle, even the most vociferous Gunner would have conceded any hopes of beating the Spanish giants.
With Arsene Wenger's departure now imminent, even the most skeptical Gunner will be forced to reconsider his position, as far as the outcome of the semi-final is concerned.
If the Arsenal side needed any more incentive to do a job against Atletico, apart from the solace of silverware in one of the most disappointing campaigns under Wenger, a need to do right by him should rekindle the spark in his set of players.
A spark that might threaten to burn down Atletico's challenge for the Europa League.
Signing-off with the Europa League isn't exactly the kind of farewell anyone associated with Arsenal had envisaged for Wenger but the prospect of leaving empty handed is far grimmer.
Therefore, we think that this might play a major role in the outcome of not just the first leg in London but also the whole tie, with each Arsenal performance from here-on-in a tribute to the Le Professeur.