(CNN) -- Manchester United will be without Wayne Rooney for Sunday's English Premier League clash with Blackburn, but manager Alex Ferguson expects the England striker to return from injury next weekend.

Rooney made a shock comeback in Wednesday's Champions League clash with Bayern Munich, but had to go off with an hour to play after aggravating his ankle problem as United crashed out of Europe's top club tournament on away goals.

Ferguson believes the injury is not serious and that Rooney will be fit for second-placed United's clash with local rivals Manchester City next Saturday.

"I don't think it's as serious as we said when he got the injury the first time, but I think he'll be ready for the City game," the Scot told reporters on Friday. "We've got more time to work on it, anyway. Other than that, everyone else is fit."

Ferguson said he was ready to put faith in Dimitar Berbatov for the short trip to North-West rivals Blackburn, despite keeping the Bulgarian forward on the bench until the final 10 minutes of the 3-2 win against Bayern.

"Yes, I still trust him," Ferguson said. "He is a good player and there is absolutely no reason why we should doubt that.

"Dimitar has done well in a lot of games recently but we prefer to play with one striker. When we got the man sent off on Wednesday there was no need to bring a striker on because all we were trying to do was go over the line in terms of defending."

Ferguson hinted that he will rotate his squad as United seek to win and move a point above leaders Chelsea, who take on Aston Villa in the semifinals of the FA Cup on Saturday.

"Given the nature of the game on Wednesday and the energy spent, we have to address the situation of freshness," he said. "We've got a a squad to use -- we have the likes of Paul Scholes, Ryan Giggs and Gary Neville and we also have John O'Shea back now.

"He came on against Bayern and did 30 minutes' work -- it's good to get him back because he's such a versatile player for us."