Wenger also confirmed that Belgian defender Thomas Vermaelen will certainly not travel to Stamford Bridge, having failed to recover from an Achilles injury, and Abou Diaby remains a doubt with an ankle injury.
"I don't know about Cesc" said Wenger. "It looks a 50:50 but a 50:50 balancing on the negative side. I will find out on Saturday morning."
Wenger conceded earlier this week that his captain had "little hope" of featuring against the champions, but it seems as though the World Cup winner will be given every opportunity to play.
Fabregas injured his hamstring in the process of scoring a freak goal against Sunderland at the Stadium of Light two weeks ago, when a clearance by Anton Ferdinand ricocheted off him and into the net.
Wenger will give Diaby every chance to be involved on Saturday. The Arsenal manager said: "Abou Diaby has an 80% chance to be involved. I am not sure if he will be completely 100% but it is 100% he will be in the squad."
Manuel Almunia, who has not trained since conceding three goals against West Brom last weekend, missed Tuesday night's Champions League win over Partizan Belgrade with an elbow injury, meaning Lukasz Fabianski could start his second consecutive match in goal.
Meanwhile, there was positive news about two of Arsenal's longer term injuries.