Ferguson claims Chelsea are main challengers

Ferguson is looking to win four straight league titles (GETTY IMAGES)

Sir Alex Ferguson has cranked up the pressure on Liverpool manager Rafael Benitez by declaring Chelsea to be the biggest threat to Manchester United's dream of an unprecedented fourth consecutive Premier League title.

Big things are expected of Liverpool this term after their most consistent top-flight campaign since 1990.

Yet Ferguson does not see the Merseyside giants making the improvement necessary to end their championship drought.

"Liverpool had probably their best season for 20 years and still finished four points adrift," he told The Sun.

"It will be hard for them to match last season, let alone improve on it. Other teams will know more about them, so it has to be Chelsea as the main threat."

Benitez is bound to bristle at such comments, although with Xabi Alonso about to join Cristiano Ronaldo, Kaka and Karim Benzema at Real Madrid, it is difficult to see how a Liverpool side whose focus continues to be the axis of Fernando Torres and Steven Gerrard can get better.

The arrival of Carlo Ancelotti also brings an unknown dimension to Chelsea, although Ferguson believes the Italian's past record makes him an opponent to be respected.

"Ancelotti will play the Milan way," said Ferguson.

"It brought him two European Cups - it should have been three because they should never have lost to Liverpool, so why should he change?"

That put-down of Benitez's proudest moment as Liverpool manager from Istanbul in 2005 will not endear him to the Anfield club either.

However, United have their own worries at present, namely the broken fingers Edwin van der Sar suffered during the penalty shoot-out defeat to Bayern Munich in last week's Audi Cup that will keep him out for eight weeks.

The 38-year-old's injury turns the spotlight firmly onto Ben Foster, whose own well-chronicled fitness problems have been a consistent handicap in his bid to establish himself as United's number one.

Ferguson has never lost faith in the former Stoke star, who he insists will be Fabio Capello's first-choice goalkeeper at next summer's World Cup.

Now, more than ever, Foster needs to remain healthy as it would give him until the end of September, a period that includes the opening two Champions League fixtures as well as seven Premier League games, to prove his capabilities.

He seems certain to be involved in some capacity against Valencia at Old Trafford this evening, which should guarantee selection in Capello's squad to face Holland in Amsterdam next week, and also Sunday's Community Shield showdown with Chelsea at Wembley.

Then it is on to a home game against Birmingham on August 16 as United start life without Ronaldo, sold for a world record £80million but leaving behind a massive hole for Ferguson to fill.

The United boss insists there is little point attempting to find a like-for-like replacement for the FIFA World Player of the Year.

But, despite reports linking him with a move for Valencia's best two players David Villa and David Silva, he feels his squad is good enough to cope.

"People have misread our situation and underestimated our ability to improve players," he said.

"We are expecting a lot from Jonny Evans, Danny Welbeck, Darron Gibson, Federico Macheda and the Da Silva brothers (Rafael and Fabio), while Nani and Anderson will improve this season.

"We will miss Ronaldo's goals, that is obvious. But Berbatov will do well this year and Wayne Rooney and Michael Owen are both capable of getting 20 goals."

In addition, Ferguson is still counting on top performances from his old guard of Ryan Giggs, Paul Scholes and Gary Neville.

Giggs in particular has impressed in pre-season so far, even though he is approaching his 36th birthday.

"People may say they have had their day but that is a pretty dangerous assumption," said Ferguson.

"Giggs has been out of this world in pre-season. I don't know how he does it. He still has so much energy and an incredible change of pace to go past defenders."