MANCHESTER: Rafa Benitez might claim that Sir Alex Ferguson is worried by Manchester City's incredible spending spree but the man himself appears unconcerned ahead of Manchester United's Premier League opener against Birmingham on Sunday.

Many, including Liverpool boss Benitez, are tipping City to challenge for the Premier League crown currently held by United in the wake of their 100 million pound spending spree during the close-season.

United manager Ferguson, however, insists clubs like City who want to break the stranglehold the top four have had on the English game in recent years will face a tough challenge.

Ferguson, who will hand a debut to new signing Antonio Valencia at Old Trafford this weekend, said: "This is where the interest lies. They (City) have taken us off the back pages and I'm quite happy about that because sometimes I get fed up with reading about us.

"What's going to happen? Well, the only thing that matters is the results on the pitch.

"I don't think there is a threat to the top four. They are all well established. These will be the teams we have to beat.

"I mean the top four have been well established and have got all the right criteria, experience, quality, good stadia, good squads, to me that top four will still be hard to beat."

Ferguson is still without long-term injury victims Edwin Van der sar, Owen Hargreaves and Nemanja Vidic, but could welcome back Nani after he recovered ahead of schedule from a dislocated shoulder.

Ben Foster (knee), Johnny Evans (ankle) and Rio Ferdinand (back) are all expected to be fit as United begin the defence of their domestic crown.

Birmingham counterpart Alex McLeish, however, couldn't find himself in a worse position after suffering horrendous defensive problems prior to the daunting trip to Manchester.

McLeish may have eased his left-back worries but centre-half still remains a problem area on the cusp of the new season.

McLeish has signed Gregory Vignal on a 12-month deal from FC Lens following a successful trial spell and he will go straight into the team at Old Trafford.

McLeish still needs to find two fit and capable centre backs for the showdown with the champions, with Liam Ridgewell, Scott Dann, Giovanny Espinoza and Martin Taylor all ruled out.

Full back Franck Queudrue could be switched, despite concerns about his fitness, to partner recent signing Roger Johnson, who knows his debut could well turn into a nightmare.

Johnson said: "It's not helped with all the injuries. Me and Scotty (Dann) both had off season operations and he is still not right and with Martin Taylor picking up the injury that he did it's just been carnage defensively.

"We've not been able to get any understanding with each other because I've not played with the same centre-half all pre-season. It's been difficult but in a few weeks we'll have everybody back fit."