Former Arsenal winger Robert Pires believes Arsene Wenger's squad could face their toughest challenges of the Champions League group stage when they face Dinamo Zagreb and Olympiacos over the coming weeks.
Arsenal take on Dinamo on Tuesday knowing victory is essential to keeping their hopes of progression alive, before rounding off a difficult Group F campaign with a trip to Olympiacos next month.
Wenger's men lost the two reverse fixtures and sit bottom of the group after picking up just three points from four games.
A win over Bayern Munich at the Emirates Stadium was quickly forgotten after a 5-1 hammering in Bavaria last time out, but Pires maintains Arsenal play better against more ambitous, attacking teams like the German champions.
Speaking to Omnisport, the former France international questioned: "Why does it go wrong for Arsenal in Champions League?
"First, this is simple, and we have evidence, is that when you play against Zagreb, for example, you always have to attack.
"Sometimes you even forget to defend. And generally, in this case - and it happened - you are subject to counter-attacks. And with the level of the Champions League, even against Zagreb or Olympiacos, it gives you complicated situations.
"On the other hand, when you play a team with the same level as you, a team which is similar to you, even if Bayern are better than Arsenal, I mean a team which attacks and allows you opportunities, it gives you space.
"And for a team like Arsenal, it's wonderful. It happened [against Bayern] at the Emirates Stadium. And that is a reason why Arsenal is now the only one that beat Bayern Munich.
"So, to conclude, Arsenal play better against teams like Bayern Munich than against teams like Olympiacos, who play defensively and who don't allow you space and catch you on the counter-attack."