Chelsea full-back Ashley Cole has been ruled out for up to 10 days after suffering a calf muscle injury.
Cole picked up the problem during the first half of the Blues' 5-0 thrashing of Sunderland on Saturday and was replaced by Wayne Bridge.
He did not travel with the Chelsea squad to Italy for Tuesday's Champions League tie with Roma due to the injury.
The England international is now likely to be sidelined until the end of next week after Chelsea confirmed the extent of the problem.
In addition to the Roma fixture, Cole will also sit out Sunday's Premier League trip to Blackburn. The left-back is also expected to miss the Carling Cup tie with Burnley, but should be fit to return against West Bromwich Albion on Saturday 15th November.
Blues boss Luiz Felipe Scolari will turn to Bridge for Tuesday's European encounter, with the former Southampton defender having made six appearances so far this season.
Meanwhile, Chelsea skipper John Terry has appealed to the club's fans to be on their best behaviour in Rome.
A series of security measures have already been put in place to ensure there are no clashes between the two sets of supporters, as Roma's infamous 'ultras' have been blamed for inciting outbreaks of violence with Middlesbrough and Manchester United fans in recent years.
Chelsea's supporters have already been advised that sales of alcohol will be restricted in the Italian capital and that they can expect to be searched on arrival at the Olympic stadium. They will also be kept inside the ground for an hour after the game.
Terry said: ''I want everyone travelling to be careful and sensible. Enjoy the city and the game. Let's all get home safe and with a good result.''
Two years ago, three Middlesbrough fans were stabbed while in April last year, 11 Manchester United supporters were hospitalised due to incidents before their semi-final first leg.
Last December, seven United supporters were taken to hospital after the two sides met again in the group phase but their quarter-final this April passed without problems.
The Champions League final is being staged in Rome this season but UEFA president Michel Platini has already warned it could be moved if there is any more serious violence involving Roma's fans.