Manchester United duo Wayne Rooney and Nemanja Vidic are doubtful for their Champions League semi-final second leg against Barcelona after picking up injuries in the 2-1 defeat to Chelsea on Saturday.

Vidic had to be stretchered off after Didier Drogba caught him in the face with his knee during the first half and required stitches beneath his bottom lip after losing a tooth in the incident.

Rooney aggravated a hip injury originally sustained in the 1-1 draw at Blackburn and appeared to be in considerable discomfort before being substituted for Cristiano Ronaldo.

Both players missed training on Monday, and United will give them as much time as possible to prove their fitness.

United manager Sir Alex Ferguson said: "It's a difficult one. We think both could make it but I can't be certain about that."

Ronaldo, Owen Hargreaves and Carlos Tevez all started on the bench for the game at Stamford Bridge, while Paul Scholes and Patrice Evra were left out of the squad altogether.

All will hope to start against Frank Rijkaard's side, with Hargreaves a contender for the right-back position if Wes Brown is moved to centre-half to deputise for Vidic.

Despite his contretemps with a Chelsea groundsman, Evra is certain to come in for Mikael Silvestre at left-back after his penetrative running was badly missed at Stamford Bridge.

Ferguson has tended to field a defensive 4-5-1 formation for home games in the knockout stages of the Champions League, meaning Scholes, Hargreaves, Carrick, Anderson and Darren Fletcher will compete for the three central midfield berths.

Winger Ryan Giggs, meanwhile, is under pressure from Nani and Park Ji-sung after an uninspiring performance against Chelsea saw him substituted at half-time.

Barcelona welcome back Carles Puyol from suspension, and he will slot into the centre of defence in place of Rafael Marquez, who is himself suspended after being booked in the 0-0 first leg draw at the Nou Camp.

Midfielder Yaya Toure is a doubt with an ankle injury, meaning Edmilson may be in line for a start in front of the back four.

With Ronaldinho out for the season, Lionel Messi, Thierry Henry and Samuel Eto'o could make up the visitors' front three, although young striker Bojan Krkic will hope to be involved after starting in the first leg.

Tom Williams / Eurosport