Manchester United have been hit with a virus ahead of tomorrow's derby against City with Patrice Evra, Nemanja Vidic, Dimitar Berbatov and Paul Scholes all believed to be among the victims.

The illness swept through their Carrington training complex following the squad's return from Turkey and, with Ryan Giggs ruled out with a hamstring injury and Nani doubtful after tweaking a groin, it means that Sir Alex Ferguson may have to rely on some of the untested members of his squad for the match with Manchester City at Eastlands. "It is not a great position for us to be in. We are counting heads at the moment," he said.

The Manchester United manager also confirmed that he expects Owen Hargreaves to be out for five weeks with the hamstring injury which forced him to limp off after only five minutes of United's match with Wolves on Saturday.

"We were at the stage where we knew Owen's knee was OK," Ferguson said. "His training performances for eight or nine days previously had been terrific. He had done really well, which is why we took the chance. But maybe the tension in the build-up for the lad was too much and he suffered because of it."

Despite having to contend with a depleted squad Ferguson was still confident ahead of the highly anticipated match. "There is nothing more satisfying than winning a derby game. It doesn't matter what year it is or when it is," said Ferguson, who oversaw three victories against City last season including two in the league by way of last-minute goals and one at Old Trafford in the Carling Cup semi-final second leg.

Ferguson accepted that Manchester City's resources mean that they are bound to challenge for the title but it is still a difficult league to win. "If clubs have money and want to spend it, they will," said Ferguson. "Chelsea did the same. So did Sunderland back in the 1950s. It is not an unusual thing. It is a fact of life.

"The only difference is that City is an untapped well at the moment. But it is difficult to say whether it is inevitable they are going to win the league at some point. Obviously, in many people's eyes, having the money is a lot better than not having it. But it is still a difficult league to win. City recognise that themselves."