Wenger has been impressed by Fabianski since drafting him into the side for the 2-0 win at Bayern Munich last month.
"Fabianski's reflexes, his positioning and his decision-making has been great," said Wenger. "We will decide as late as possible [on his availability.
"[Szczesny has responded] really well. He worked very hard and worked very well. I do not want to make a case of it before the game. He's handling the situation very well and in a positive way."