The 38-year-old has not featured for the Gunners since August 19 at Blackburn when he made a second high-profile error of the then fledgling season.
Wenger revealed: "Lehmann will start in goal.
"His attitude has been fantastic and when you look at this man the one thing you cannot fault is he is a super professional. Jens is an example for everybody.
"For every goalkeeper it is good to practice, but at some stage you need to play at a competitive level.
"It is not a present. It is to keep him fit and competitive.
"If Jens plays well it does not create a problem.
"Why should it be a problem if a player plays well? It is a problem if he doesn't play well."
Wenger maintained: "For all of us the only target is to do well for the club - and we can only do that if we perform well.
"Jens' long-term future depends on, when you are 38, what you call a long-term future. We haven't spoken about that.
"At the moment I expect him to play well tomorrow."
However, when asked if he expected Lehmann to remain at Arsenal for the second half of the season, Wenger said: "I cannot guarantee [that], like for anybody else."