Mikel Arteta admitted Arsenal would have to improve when they face Bayer Leverkusen in the second leg of their Champions League last-16 tie.
The Gunners, who topped the league phase after eight wins from eight games, needed a last-minute penalty from Kai Havertz against his former club to escape Germany with a 1-1 draw.
“I liked that emotionally we understood what we had to do, but the level of execution obviously has to be better,” said Arteta.
“And it will be better in the second leg. We’ll adapt a few things and move on.”
Arsenal hit the crossbar through Gabriel Martinelli in the first half, but were trailing to Robert Andrich’s goal – from a corner, of all things – seconds after the restart.
They were caught cold straight from the kick-off, first when Martin Terrier’s header had to be spectacularly tipped over by David Raya.
From the corner, Andrich gave Eberechi Eze the slip at the far post to head the hosts in front.
It was a taste of their own medicine for an Arsenal side so proficient from corners this term.
“There’s always two sides to that,” added Arteta. “One is the element of the opponent, that they picked that weakness and that lack of attention or urgency in both situations.
“And the other one is us because we knew, we showed them three clips from last weekend in three different ways and we weren’t ready for that and we got caught.”
The equaliser came when Noni Madueke got past Malik Tillman into the area and was tripped by the defender.
It looked soft, but a VAR check upheld the decision after replays showed Tillman’s hip had caught Madueke’s foot and substitute Havertz coolly converted the spot-kick to deny the club where he began his career a famous win.
“Football is a funny game and it brings special stories,” smiled Arteta. “Him coming back here after such a long time, being part of this club, to come here and score such an important goal, I think it’s a big moment.”
Leverkusen coach Kasper Hjulmand felt his side were hard done by.
“Disappointed with the penalty at the end. I don’t see a penalty there but that’s the way it went,” he said.
“I think sometimes the referee shouldn’t blow the whistle and then check with VAR. If he whistles and it’s not clear and obvious then it stays. But for me, it just wasn’t.”
Leverkusen’s social media team had poked fun at Arsenal’s reliance on set-pieces by posting a photo of a sign reading “no corners allowed”.
After their goal, they added “well, this is awkward…” while Hjulmand was seen chatting to Arsenal’s famed set-piece coach Nicolas Jover on the touchline.
“It’s not our first goal in that way,” added Hjulmand. “He was just looking at me like ‘you do it too’.”
