Wojciech Szczesny admits that a damaging five-minute spell at Swansea City cost Arsenal the game.
The Gunners looked in charge when Alexis Sanchez gave them lead, but two quickfire goals from Gylfi Sigurdsson and Bafetimbi Gomis condemned them to defeat.
Szczesny was particularly disappointed as he felt that the team had performed well up until that point.
"You can’t just hope that the next one will be different and we’ll get a bit of luck - we need to focus for 90 minutes and do our jobs"
“For the majority of the game we looked solid at the back and we looked dangerous,” the goalkeeper told Arsenal Player. “We had a poor five-minute spell and at this level it costs you.
“Until they scored their first we were good. Then after they scored the second goal we looked dangerous again, so it was the five minutes that cost us the game.
"It’s something that we need to focus on because it’s been two games where short spells lacking discipline and focus have cost us.
“It could’ve gone either way but it didn’t. You can’t just hope that the next one will be different and we’ll get a bit of luck - we need to focus for 90 minutes and do our jobs properly offensively and defensively. Then things will change.”