Alex Ferguson insists form will play no part in what he deems Manchester United's biggest fixture on Sunday - a clash with Liverpool. United are in much the better shape as they prepare to face their great rivals at Anfield, even though they look likely to be without striker Wayne Rooney.

Ferguson's men are top of the Barclays Premier League and well on course for a place in the knockout stages of the Champions League.

In contrast Liverpool are lurching towards a crisis after a run of four successive defeats which has left them struggling to maintain interest in both competitions.

Yet Ferguson has faced Liverpool enough times during his long tenure at Old Trafford to know to expect the unexpected.

The Scot said: "Manchester United and Liverpool games, as I have said many times, are without question massive games. That will never change.

"It is the kind of game when I came to the club 23 years ago, I thought 'Yeah'.

"In my first derby game with them I got a complete sense of the history of both teams and it hasn't changed. It is still a massive game.

"It is the game as far as I am concerned, that won't change.

"We are going in decent form, there is good confidence in our play, but it is a derby game and anything can happen in derby games.

"Going to Anfield at any time is a hard game."

Victory for United would add considerably to the growing pressure on Liverpool manager Rafael Benitez.

Yet Ferguson, subject of a remarkable attack from Benitez last season, is quick to point out that is no concern of his.

"I'm not interested in Liverpool," the 67-year-old said. "I'm only concerned about what we do on Sunday."

United comfortably held off Liverpool to take the title last season, even though they lost twice at the hands of Benitez's men.

The second of those occasions was a 4-1 humbling at Old Trafford but, having had the last laugh by equalling Liverpool's record of 18 league wins, Ferguson does not feel there are scores to settle.

He added: "I don't see that we have a point to prove. Different games are shaped by circumstances of games.

"You can't look at last season as a barometer of our form or Liverpool's form. Derby games are derby games and anyone can win it.

"Strange things can happen. It has happened so many times."

Rooney remains doubtful for United as he continues to struggle with the calf injury sustained during England's World Cup qualifier in Ukraine a fortnight ago.

The striker will be assessed on Saturday - his 24th birthday - before a decision is taken on whether to include him in the squad.

Ferguson said: "He is always desperate to play. That is the nature of the boy, you won't stop that.

"It is important how he does in training tomorrow. If he does train tomorrow we will have a better idea."

Ryan Giggs and Patrice Evra are both poised to return after suffering knocks against Bolton last week but Darren Fletcher is also doubtful and Park Ji-Sung is definitely out.

United's own performances have been questioned at times this season, most recently after an unconvincing 2-2 draw with Sunderland earlier this month.

But Ferguson feels his side are now stronger for the recent return of veteran goalkeeper Edwin van der Sar.

The start of the 38-year-old Dutchman's season was ruined by a hand injury but he came back against Bolton and also featured in the midweek win at CSKA Moscow.

Ferguson recently heard his number one described as the game's best goalkeeper on a TV programme and is in full agreement.

"Ruud Gullit said he was the best in the world and got no argument from the rest of the panel," Ferguson said. "His argument was quite right - look at his record over the years. His experience, his composure, his organisational ability - he really is a fantastic goalkeeper. He does make a difference to us."