Pires was speaking about the club's chances of winning the competition that would give them a direct entry into the Champions League.
Pires said: "Atletico and Arsenal are the favourites, for me this is the final in Lyon.
"They both have a lot of experience, especially in the Champions League.
"They just need to avoid each other and Celtic if they want to face each other in the final.
"That's why it is very difficult to win in Celtic Park."