Arsenal threw away what would have been a third straight European victory, and all but securing safe passage into the Champions League knockout stages, when they allowed AZ Alkmaar to snatch a stoppage-time equaliser in Holland on Tuesday night.
However, Abou Diaby maintains the Gunners can only learn from their mistakes to be stronger in Europe this season.
"We will take a good lesson from this," said the midfielder.
"We need to stay focused until the last minute, so we need to work on that.
"We can still improve in these situations, to be focused on the second ball.
"Now we need to look to the game against West Ham, and be ready for the challenge."