Manchester United boss
Sir Alex Ferguson accepts they
face a difficult task to win a fourth consecutive
Premiership title this
season.
He said: "Winning four titles is something we'd like to do and
it would be a great achievement.
"We know how difficult it is to win this league. We accepted a
good challenge last season in terms of having to go to Japan [for
the Club World Cup] and then play catch-up and to win the league
was a great achievement.
"We don't have that problem this season, although I wish we did.
But [trying to win four titles in a row] is still a great challenge
for us."
Ferguson added: "It's difficult to say [who the biggest threat is].
I think ourselves, Liverpool,
Chelsea and Arsenal are looking at what's happening at
Manchester City with great
interest and whether it can work in terms of the money they've
spent.
"They're on the back pages every week now and there's a lot of
interest in their situation particularly as none of us have really
gone into the market in a big way. We've sold players in fact -
Liverpool sold Alonso, we've
sold Ronaldo, Arsenal sold Adebayor ... the big four have
actually been really quiet [in terms of buying].
"So we're all interested in how it's going to pan out at
City."