The France playmaker has been the Gunners' form player this season, playing the best football of his four seasons in England. He is the club's top scorer in all competitions with 14 and would significantly raise their hopes of toppling the side Wenger rates as the best in the world.
Nasri suffered a hamstring injury in the FA Cup fourth-round match against Huddersfield and has been on the sidelines for the last two weeks. It was thought he was at least another week away from fitness but Wenger revealed he was surprisingly in contention for the home leg against Barca.
Wenger would be loathe to take any undue risks with the player but knows from their meeting in last season's quarter-finals of the same competition with the Spanish champions that a positive result in the home leg is imperative.
A 2-2 draw at the Emirates was not good enough last time, with Barca comfortable winners at the Nou Camp.
"I would say he has a chance,'' said Wenger. "He has tests, one tomorrow and one on Tuesday. I will not take a crazy gamble but physically he has worked very hard; physically he is ready. It is just if there is a risk of a setback or not.''
Asked if the 23-year-old was eager to face the La Liga giants, Wenger added: "Who isn't? But we have the Carling Cup final too... we have so many big games it is important not to be stupid as well.''
Wenger opted to ease Robin Van Persie back from his injury problems and has been rewarded in some style by the Dutch striker. He has now scored 11 times since the turn of the year and Wenger believes his rich vein of form could be important to Arsenal in midweek.
"It took him some time to get back to good form. We used him well, not rushing him back,'' he said. "He was getting back to his best and he is at his best.
"We go into the Barcelona game in better shape than last season and Robin is part of that. We had many uncertainties last year and now the team has more confidence. We have matured better. We can compete better with them technically.''