Diego Simeone was left frustrated by his Atletico Madrid side's costly mistakes in their Champions League defeat against Arsenal.

The Gunners opened the scoring in the 57th minute through Gabriel Magalhaes, before Gabriel Martinelli's neat finish and Viktor Gyokeres' quickfire double saw the hosts go 4-0 up, with all four goals coming in a period of 13 minutes and 51 seconds.

It marked Atleti's joint-heaviest defeat in the Champions League; it’s the fifth time they’ve lost by a four-goal margin in the competition and first instance since October 2024 at Benfica (0-4).

The LaLiga side have now lost 10 of their last 16 away games in the competition (W4 D2), and five of their last six games in England (W1).

With two of Arsenal's goals coming from set pieces, another going in via a deflection off David Hancko, Simeone was less than impressed with how his side faltered in the second half.

“We competed very well until the first Arsenal goal, then we couldn’t compete,” Simeone said, in his post-match press conference.

“It can come down to fine margins in terms of taking the game into your control or not and it’s not down to bad luck, it’s down to mistakes. They made the most of our mistakes. They took their chances and all their big chances turned into goals.

”We could have scored with Julian Alvarez in the first half, he hit the bar in the second half, we competed well as a team but this is a lesson we can learn. You have to be clinical in different phases of the game.

“It’s individual mistakes that affect the team, it’s losing your man in a set-piece, for the third goal we were too meek and ended up conceding a goal from that.

“These are small details that can turn the game in one team’s favour... there are situations we can resolve collectively but when it comes to individual decisions, it’s hard to help with that.”