Chelsea manager Carlo Ancelotti may now delve into the transfer market in January after Jose Bosingwa was ruled out for three months.
The 27-year-old defender has been out since mid-October with a knee injury and will now not return until the new year.
A statement released on chelseafc.com read: "Chelsea Football Club can confirm that Jose Bosingwa underwent arthroscopic surgery on his left knee this week. His recovery time will be approximately three months."
Portugal international Bosingwa has made eight appearances for Chelsea this term, the most recent of which came when he was taken off in the second half of the 2-1 loss to Aston Villa on October 17.
Blues boss Ancelotti, whose side lead the Barclays Premier League by five points from Arsenal and Manchester United, was adamant he was happy with the squad following the Court of Arbitration for Sport's suspension of the FIFA transfer ban imposed over the club's recruitment of Gael Kakuta from French club Lens.
But he may now be forced into a re-think by recruiting to maintain the Blues' title charge.
Didier Drogba, Salomon Kalou, Michael Essien and John Obi Mikel are all set to miss most of January because of their participation in the African Nations Cup and the latest blow with Bosingwa leaves Chelsea with limited options.
The news about Ashley Cole is brighter, although a time scale for the left-back's return is yet to be made public.
The 28-year-old withdrew from the England squad for Saturday's friendly with Brazil in Qatar after playing a full part in the Blues' 1-0 defeat of Manchester United at Stamford Bridge last Sunday.
The left-back had missed three games after initially sustaining the injury in the 4-0 home win against Atletico Madrid in the Champions League last month.
He returned against Madrid in the return Group D game last week but required a pain-killing injection in order to play against United.
Chelsea were, however, buoyed by the news that he does not need to go under the knife following a shin injury.
"Meanwhile, Ashley Cole is suffering from an aggravation of a depressed fracture of the tibia, originally picked up against Atletico Madrid at Stamford Bridge," the statement added.
"The injury will not require surgery."
Drogba has withdrawn from the Ivory Coast's final World Cup qualifier against Guinea on Saturday, although Chelsea have yet to confirm his absence.
The striker remained in London for treatment after sustaining a chest injury in a clash with United's Jonny Evans at Stamford Bridge.
Drogba may be fit enough to play in next Wednesday's friendly international against Germany in Gelsenkirchen for the World Cup-bound Ivorians.Reuse content