Arsene Wenger says the injury to Jack Wilshere is not as serious as first feared but cannot say when he will return to training.
The 20-year-old has not figured for the Gunners this season after struggling with an ankle problem but it was hoped he would be fit enough to return in February.
However the midfielder suffered a setback in training on Friday and is facing and extended spell on the sidelines.
Wenger does not believe the problem is serious though and hopes to have him back available sooner rather than later.
"We have no real news yet. The first news we have had is better than expected. He is not in a boot, but I don't know more," Wenger revealed after Sunday's 3-2 FA Cup win over Aston Villa.
"His morale looks quite good and I hope it will only be a short setback. There will be more tests this week. I do not know yet when he will start training.
"I would not like to make any mistake in my statement because I did not speak to the medical people today."