Chelsea captain John Terry could be out for up to six weeks following surgery on a back injury, according to a medical expert.
The 26-year-old has not featured in the Blues' last three Premiership matches, in which they have conceded six goals to lie four points behind leaders Manchester United.
Chelsea confirmed the England skipper had gone under the knife to remove a sequestrated lumbar intervertebral disc in France following consultation with a neurosurgical specialist.
A statement released by the club claimed the operation had been a success, but medical expert Phil Sheard believes Terry will face a month or more on the sidelines as he recuperates from the surgery.
'A couple of weeks is the most optimistic,' the consultant orthopaedic spinal surgeon told Sky Sports News. 'Realistically you are looking at four to six weeks before he will be back playing football.
'In most cases, these will get better by themselves. But we quite frequently do operations so that we can get people back to work quickly - and I think that is what has happened here.'
A speedy return would be welcome news for manager Jose Mourinho, who has made no secret of his desire to get Terry back in action as soon as possible.
It also remains to be seen if the defender will be fit to lead his country in their first international of 2007, against Spain at Old Trafford on February 7.
In the continued absence of their inspirational centre-half and goalkeeper Petr Cech, the Blues have looked somewhat shaky in defence. Chelsea have now let in 15 goals - only seven fewer than they did over the whole of the last Premiership season.
Having sold both William Gallas and Robert Huth, Mourinho admits the continued absence of the England captain has left him short of options in the heart of the defence.
The Chelsea manager has even considered asking 19-goal striker Didier Drogba to step into the role on an emergency basis.
The 28-year-old said: 'I do not like to play at centre-back - but I do it for the team because sometimes we have difficult moments in the game.'
Drogba believes he has finally silenced the critics who doubted his ability to make the grade in English football.
The Frenchman currently leads the Premiership scoring charts with 12 goals after his brace against Reading in Boxing Day's 2-2 draw.
Those goals took his tally to 51 in 85 starts since signing from Marseille in summer 2004 - a good return for a player who was initially belittled as a £24million flop after an inauspicious start in west London.
'It's not bad for a player who has been criticised for the first two years,' he told Chelsea TV.
'I'm happy because I could maybe have scored more goals, but it's always difficult. The teams you are playing against are strong.
'I think I have been here for a few years now and it is a good ratio.'