Aston Villa defender Martin Laursen is hoping he could be back in action within a month after suffering suspected medial ligament damage during the Carling Cup clash at Chelsea on Wednesday evening.
The Danish international, who has been plagued by knee problems, had to be substituted at half-time during the 4-0 reversal at Stamford Bridge following a collision with Didier Drogba.
Laursen will not know for certain the extent of the damage until undergoing a scan but is cautiously confident he could return sooner rather than later.
He said: 'It was an accidental incident with Drogba. I wanted to get the ball but I fell badly and got a twist in my right knee and felt pain straight away.
'It's the medial knee ligament and I can't say at the moment how serious it is, but it's sore.
'It felt loose when they tried to test it so something is wrong. They say it will be at least three weeks if it's not that bad.
'But I'll see how bad it is when I've had some tests on it.
'It's the good knee so at least that's something which is a relief. I've not had a serious injury in my right knee before and I hope this isn't one now.'
Laursen added: 'I'm very disappointed to be injured again because I feel I'm in very good physical shape, I did well against Blackburn and I thought I did well last night up until the injury.
'It's never the right time to get injured but I'm disappointed now because I've been playing well and feeling good so it's a shame.'
Manager Martin O'Neill will also be sweating over the fitness of skipper Gareth Barry who also did not reappear for the second half after suffering a back injury in an aerial challenge with Chelsea defender Ricardo Carvalho.
Midfielder Barry, who will also undergo a scan, has been pushing hard for an England recall after a series of fine displays.
O'Neill said: 'Gareth took a knee to the back and it's very sore. We'll have to wait and see how long it will be a problem for.'