Arsenal manager Arsene Wenger admits he is in the dark about Tomas Rosicky's return from injury after complications with the midfielder's comeback.
The Czech international suffered a knee injury against Newcastle in January which also ruled him out of the Euro 2008 finals in the summer.
Complications with the injury have led to the 28-year-old missing the start of Arsenal's season at a time when Wenger lacks experience in his inexperienced midfield.
Wenger believes Rosicky is recovering well from the injury but admits his comeback match is still uncertain.
"I believe that all the checks we made are reassuring, but it's difficult to say," Wenger told the club's official website.
"It's an inflammation that's going on in his leg that has to settle, to calm down.
"We are a little bit speechless on that at the moment because we feel it is all going well. It is a problem of re-coordinating his muscle with the exercises he does.
"There's nothing really that harms his future, but, as well nobody can tell me on the 10th of December he will play.
"He can be on the 31st of December, he can be on the 10th of November, nobody knows with him.
"In the next two months he should be back but what date, nobody knows."