The Colombian, goalkeeper who was the Gunners' first choice for the majority of the last season, has only featured in cup games for the North Londoners so far this campaign but is expected to start in Tuesday night's Champions League game against Olympiakos.
Wenger said: "This is not just because I have decided Ospina plays in the Champions League. It will go game by game and there can be a different decision.
"I need to give him games. He is a top-level goalkeeper. It is of course harsh that he is on the bench.
"But that's our job, selection and competing with other players. He does that extremely well. I am fortunate to have two goalkeepers of this quality."