Mikel Arteta warned his Arsenal players they must improve their set-piece defending "dramatically" after they were held to an entertaining stalemate by Sporting Lisbon.
William Saliba opened the scoring with a brilliant header on 22 minutes but Goncalo Inacio and Paulinho struck either side of half-time to turn the Europa League last-16 tie on its head. Sporting had chances to extend their lead but a Hidemasa Morita own-goal from Granit Xhaka's cross just after the hour mark levelled the scores, leaving the tie finely poised ahead of next Thursday's second leg.
Matt Turner had a game to forget in the Arsenal goal; his indecision allowed Inacio a free header from a corner and his poor parry gave Paulinho a simple tap-in to put Sporting ahead for the first time.
After the match, Arteta was asked whether he is concerned by Arsenal's defending of set pieces and responded: "It is something we must improve, dramatically, in the next few matches if we want to be winning games."
Arteta was also aghast with the Gunners' lax approach in possession - but insisted there were positives to take into the return leg. Speaking to BT Sport, he added: "Considering you concede two goals away from home and still escape with a draw, you have to take some positives, but we gave them too much hope by giving the ball away in our own half too many times.
"We had control for long periods but we lacked a bit of that final touch, but we are missing four key attackers, so we will take the draw. At 2-1, we lose the runner and they had a chance to make it 3-1. [There are] A lot of things to improve but we showed a lot of resiliency and we are still in the tie.
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"Making six changes, you lose a bit of the cohesion, but we had to make the changes because some are unavailable and others had to play out of position. But they did well."
Meanwhile, Saliba praised Jakub Kiwior after lining up alongside the Pole, who was making his debut after joining the Gunners from Spezia in January. "It is his first game and he played well and we played well together," Saliba said of his centre-back partner, "but unfortunately we conceded two goals. We train a lot together because we change the pairs a lot in training."
On the result, the Frenchman added: "It is okay. We wanted to win here but we didn't lose and we have to focus on the next game and we are lucky to play at home. We will try to win again.
"We know they can score but we know we can always come back and never give up. It is a good mentality from the team. It is always better to lead but when we don't, we have to come back."
