Arsenal manager Arsene Wenger admits Cesc Fabregas is 'very impatient' to return to action but insists the midfielder will not be rushed back too soon.
The 20-year-old has been sidelined by a hamstring problem since limping out of the Champions League clash in Sevilla on November 27.
Fabregas had been in superb form before his injury, netting 11 goals as the Gunners climbed to the top of the Barclays Premier League and qualified for the last 16 in Europe.
The Spaniard has already missed matches at Aston Villa, Newcastle and Middlesbrough, while he will also sit out the final Champions League Group H game with Steaua Bucharest at Emirates Stadium tonight.
Wenger revealed there was no guarantee his star man would be back for the visit of Premier League title rivals Chelsea on Sunday either.
'We haven't set any date for his return yet,' said the Arsenal manager.
'Cesc is not with the group at all; he is with the medical people being treated. He is working very hard.
'Cesc is very impatient, but he is not back yet.'
As well as Fabregas, Arsenal have several other players still on the treatment table, including Alex Hleb and Mathieu Flamini.
However, striker Robin van Persie is set to make a welcome return after being out with a knee problem since October 7, and midfielder Abou Diaby has recovered from a back injury.
Veteran keeper Jens Lehmann is also in line for his first appearance in almost four months.
Wenger - who must serve a one-match touchline ban after his sending-off in the last game away to Sevilla - indicated he will make some changes, with young Dane Nicklas Bendtner set to lead the attack.
The 19-year-old spent last season on loan in the Coca-Cola Championship with Birmingham, and intends to repay the faith shown in him by Wenger.
'Every time I get my chance I want to take it, to show people what I can do,' said Bendtner, who scored his first European goal in the 7-0 demolition of Slavia Prague during October.
'When you are in a team which plays such great football like Arsenal, it is really difficult to get into the side, but when your chance comes you have to show you are capable of coming in and playing in the team.'
Bendtner reflected: 'I will just take it as it comes. So far I have been pleased.'
Wenger knows his men must put on a performance following a below-par display at Middlesbrough last Sunday, when they lost their unbeaten Premier League record.
He said: 'My squad is very determined and very strong.
'If you had listened to what people said before the season, we would be 10th or 12th in the league and be out of everything.
'At the moment we are in everything. It is not a coincidence - it is down to the mental strength of my team.'