Meetings between the two sides have in recent years played key parts in the championship with the last seven titles having been won by one of the two clubs.
But when they meet in London on Sunday it is a different story as Chelsea are a hefty 12 points off the pace in fourth place and all but the most optimistic fan would rule them out of contention for the title.
With the best away record in the league, having lost one and won eight of 11 games, United head to London in good shape to pick up three points that would take them top of the league if leaders Manchester City fail to beat Fulham the previous day.
"Hopefully our form will stand up as it did in the Arsenal game," Sir Alex Ferguson told a news conference on Friday, referring to their 2-1 win at Emirates Stadium in their last away game in the league two weeks ago.
"It's not an easy game going to Stamford Bridge, we've not beaten them since 2002... the last seven years we've fought with them for league titles so you expect it to be a hard game and it will be."
Ferguson's men beat Chelsea 3-1 at Old Trafford in September in what he called a "crazy" game where "it could have been 20-18," but he was not expecting a repeat even if the Londoners were still adjusting to life under manager Andre Villas-Boas.
"I don't think it will be anything like that, I think it will be much tighter, I'm sure of that," Ferguson said.
"I noticed when we played them in the home game that there are changes in style from the previous Chelsea teams.
"When a new manager comes in that's always the problem... changes maybe take time. If he wants to play his way - and everyone has a different philosophy and a different way of doing things - that's what we're seeing with Chelsea at the moment."
Villas-Boas replaced Carlo Ancelotti last June with mixed results. While their league form has been faltering, they have qualified for the Champions League knockout stage while United suffered an embarrassing group-stage exit.
'BIT BETTER'
United, whose Premier League title defence has been hampered by a lengthy injury list, will be boosted for the Chelsea game by the return to the squad of long-term absentees Ashley Young and Tom Cleverley, as well as Nani and Wayne Rooney.
Winger Young has been sidelined for several weeks with a knee injury, while midfielder Cleverley has been out of action since October with an ankle problem.
"We're are a bit better this week... we hope that Rooney, Nani, Young, Cleverley will all be in the squad," Ferguson said.
"It is more likely Tom will play against Chelsea reserves on Monday but he is travelling with the team anyway."
Goalkeeper David de Gea missed the side's midweek victory over Stoke City but is expected to return to action in place of the injured Anders Lindegaard, who played in six of seven matches between December 21 and January 22.
"It looks like Lindegaard will be out for at least four wee
