Trailing LaLiga leaders Barcelona by 25 points, Diego Simeone's side have just the UCL to concentrate on winning, after being beaten in the Copa del Rey final by Real Sociedad.
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Trophy options running out for both teams
Arsenal's title options are also running out after they were knocked out of the FA Cup by Southampton, were beaten by Man City in the Carabao Cup final, and, although they lead the Premier League, the Gunners will likely lose the title if City win all their remaining games.
In the league phase earlier in this season's competition, the North Londoners wiped the floor with the Rojiblancos, thanks to a four-goal blast in the space of 14 second-half minutes at the Emirates Stadium.
Viktor Gyokeres led the way in that game with two goals, and the match represented the last time that any team in this year's competition had stopped Atleti from scoring.
Julian Alvarez, a player that Flashscore transfer expert Dean Jones has noted Arsenal are interested in, had scored nine UCL goals in 2025/26 ahead of this game, and would undoubtedly be a thorn in the visitors' side given half a chance.
Alvarez on fire in the opening exchanges
Simeone had actually made four changes from the team that knocked out Barcelona in the last round, with Jan Oblak, Marc Pubill, David Hancko, and Johnny Cardoso coming in for Robin Le Normand, Clement Lenglet, Juan Musso, and Nahuel Molina.
Mikel Arteta had only swapped out Eberechi Eze and Cristhian Mosquera for Ben White and Martin Odegaard.
Alvarez was certainly the liveliest of any attacking player in the first half, firing off three attempts before half an hour had been played.
The Argentinian's movement, appreciation of space, and innate knowledge of the position of his colleagues caused untold problems for the Gunners' defence in the early stages, and was a chief reason why Piero Hincapie made a number of interceptions.
Two different ways of playing
Indeed, by the end of the night, the defender's four interceptions were almost half of the total of nine from the entire Arsenal squad.
Only Declan Rice managed to match his colleague with two tackles during the game, whereas eight Atletico players attempted at least two.
What that demonstrated was a clear delineation between the modus operandi of the two teams.
Although it has been suggested that Arteta had been overly defensive in recent games, the North Londoners are still revered for the way in which they pass the ball around, whereas Atleti are rightly renowned for a much more physical and combative way of working.
Madueke catches the eye
Three attempts from Odegaard, Gabriel Martinelli and Noni Madueke suggested that Arsenal had something to offer in an attacking sense, albeit that all three weren't on target.
Madueke's attempts to make inroads certainly caught the eye, however, and aside from his six touches in the Atleti box - the most from a Gunners perspective - his 20 completed passes from 22 attempted, and two chances created, were a standout.
The hosts were struggling to get any sort of passing game going, and yet their sheer effort and will to win were laudable.
For example, both Alvarez and Ademola Lookman won the majority of their 10 one-on-one duels, whilst Koke, Hancko and the effervescent Marcos Llorente won back possession an astonishing 19 times between them.
Gyokeres gives Arsenal the lead
In the lead-up to half-time, with both teams seemingly content on going in level at the break, Gyokeres won and then converted a penalty to give Arsenal a vital lead.
Once again, however, it would be his only contribution of note, given he had just 15 touches of the ball in the time he'd spent on the pitch, by far the worst of any player on the night, including all but two substitutes from each team.
Given that Arsenal had won all 10 previous UCL matches in 25/26 when opening the scoring, the onus was firmly on Atleti to go out and get something from the match, rather than sitting back and expecting to play a counter-attacking game.
Matteo Ruggeri had created three chances before the break, the most from any player on either side, but thanks to Arsenal's defensive excellence, David Raya's brilliance in goal and profligacy from the hosts, Atleti went in behind.
Alvarez penalty a just reward for Atleti's dynamism
To the Rojiblancos' credit, they came out firing on all cylinders in the second half.
Not only did they dominate possession, with 67% collectively leading up to the hour mark, but they also had five attempts at goal (Alvarez, Lookman, Llorente, Antoine Griezmann x2) before Ben White's handball, which earned Atleti a 54th-minute penalty.
Alvarez slammed home the spot-kick for his 10th in the competition this season, and that only seemed to spur them on, as Griezmann hit the woodwork and saw another effort deflected wide, whilst Hancko and Johnny Cardoso also saw their chances come to nothing.
Arsenal were evidently being overwhelmed in midfield, with Martin Zubimendi winning only one of his five duels, and he, Rice and Odegaard not getting the chance to dribble at all during the match.
VAR overrules second Gunners spot-kick
It prompted Arteta to make a triple substitution, as Martinelli, Madueke and Gyokeres departed, and Bukayo Saka, Gabriel Jesus and Leandro Trossard came in.
Though the visitors then had five more attempts before the end of the game, none were close to troubling Oblak.
Arsenal were unfortunate, however, to see a penalty that had been given by referee Danny Makkelie reversed after a VAR check, as images would show Eze was definitely caught by Hancko as he lunged for the ball.
With the second leg to come, it's as you were, and both sides know that a commanding performance at the Emirates will see them into the final.
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