Manchester United have confirmed that Nemanja Vidic suffered a broken collarbone against Blackburn Rovers on Saturday.

The 25-year-old Serbian international fell awkwardly during the first half of the match at Old Trafford and after the game Sir Alex Ferguson suggested he would be unavailable for four to five weeks. If it is the latter, it would effectively mean the end of Vidic's season.

The news adds to Ferguson's defensive woes ahead of Wednesday's crucial Champions League quarter-final first leg against Roma, with Gary Neville and Mikael Silvestre also on the sidelines through injury.

Patrice Evra, who has been out since the victory at Liverpool at the beginning of last month with a hamstring complaint, is expected to take his place in the squad, providing a timely boost for Ferguson.

The United manager may field Evra at left-back and push Gabriel Heinze into centre-half alongside Rio Ferdinand, or move Wes Brown in from right-back, where he has been deputising for Neville. If Evra does not recover in time, Craig Cathcart, an 18-year-old defender yet to make a first team appearance, will be in line for a place on the bench.

Louis Saha is unlikely to travel with the Manchester United squad to Italy. The French striker has missed five weeks with a hamstring injury and although he is considered fit enough for a substitute's role, Sir Alex Ferguson wants to ease him back into the action.

United face Portsmouth at Fratton Park on Saturday before playing Roma again the following Tuesday at Old Trafford, and three first team games in six days is thought to be beyond the player, who has started just two matches since injuring his groin against Newcastle United on New Year's Day.