Manchester United have confirmed Mikael Silvestre has dislocated his right shoulder.
The French defender suffered the injury after falling heavily during the latter stages of United's 1-0 Champions League win over Lille at Old Trafford last night.
Silvestre, who had been preferred to Gabriel Heinze in Sir Alex Ferguson's starting line-up, was immediately taken to hospital for a scan.
And United have confirmed Ferguson's original belief that the 29-year-old had suffered a dislocation.
Although club officials have not put a time scale on Silvestre's likely recovery, Chelsea defender Khalid Boulahrouz was back on the bench for the Blues' win over Porto on Tuesday less than three weeks after suffering a similar injury in an FA Cup tie against Norwich.
Silvestre will definitely miss Saturday's FA Cup quarter-final tie at Middlesbrough and the Premiership home game against Bolton on March 17th after which the domestic campaign is halted for a two-week international break.
It is the latest in a series of injuries over the past 10 days for Ferguson and his team.
Ole Gunnar Solskjaer has been ruled out until the end of the month following minor knee surgery, Darren Fletcher will be sidelined for two months with ankle ligament damage, while Louis Saha could be out for four weeks after damaging a hamstring in training on Tuesday.
In addition, Henrik Larsson plays the last competitive game of his 10-week spell at the Riverside Stadium this weekend, with all attempts to persuade the Swede to stay on having failed.
