Sir Alex Ferguson is wary that Chelsea could come up on the rails and take the Premier League title.
Avram Grant's side are nine points adrift of Arsenal and six behind United but have a game in hand on both their rivals.
Ferguson takes his team to Fulham tomorrow, insisting the title race will be tight and tough.
'The number of points Chelsea are behind Arsenal is not insurmountable because in this Premier League points can be dropped,' the United boss told www.leaguemanagers.com.
'The fact that they have got us and Arsenal at home, and their home record is so good, you would have to think they have still got a big chance in the Premier League.'
Ferguson, however, believes Chelsea would be happier winning the Champions League rather than the domestic crown.
He said: 'I think that is what they are really after given Roman Abramovich's contribution to their rise in the last few years.'
Ferguson, meanwhile, is adamant United will continue to allow their players to express themselves as they chase a second successive title.
Certainly, they go to relegation-threatened Fulham in good heart after the 5-1 thumping of Newcastle at St James's Park at the weekend.
With the likes of gifted young stars like Cristiano Ronaldo, Wayne Rooney, Carlos Tevez, Anderson and Nani on their books, it is little wonder the manager looks forward with optimism.
He said: 'The players have that joy of being at a club with a lot of ambition.
'It is good to see young players having the energy and the commitment to try and enjoy themselves.
'We work hard at making sure that they are relaxed in that respect with a responsibility to use their talents all the time to express themselves.
'We are fortunate in that it is easier for them, than a lot of other players because they are exceptional talents.'