Arsenal manager Arsene Wenger says his defensive department gifted Stoke City an "early present" after his side lost 3-2 against the Potters.
The Gunners produced a superb comeback in the second half but it wasn't enough as they suffered their fourth defeat in the English Premier League.
"Stoke started strong and we were not decisive enough in our defensive challenges," Wenger said in his post-match press conference.
"From then on we gave them an early present and after that put a lot of energy into the game.
"In the second half we had good opportunities to come back and we couldn't. Overall we put a lot of energy into this game like we always have recently and unfortunately we missed our start.
"We were slow at the back and when we started to respond it was too late in the game.
"They started strong, we have to give them credit for that. We were a bit inexperienced at the back - we couldn't play [Laurent] Koscielny or [Nacho] Monreal and we had [Mathieu] Debuchy out as well.
"We were altogether maybe a bit soft to cope with what they offered us.
"That [failing to keep a clean sheet] shows that in every single game you have to be committed and focused from the first minute onwards.
"We were a bit unlucky because the third goal was a foul on the corner. Still, we were defensively not good enough today."