Already 15 points behind leaders United and 11 adrift of second-placed Arsenal, Chelsea's hopes of retaining the title are long gone and instead they must focus on fighting it out with Manchester City and Tottenham Hotspur for the remaining Champions League berths.
Chelsea have not finished outside the top four since 2002, the year before Roman Abramovich took them over, and after subsequently failing to land the Champions League trophy he so desperately wants, the Russian billionaire is unlikely to be impressed by the prospect of the Europa League.
United have 60 points, four clear of Arsenal. City are third on 50, with Spurs on 47. Chelsea, on 45, have a game in hand on Spurs and the top two and two in hand over City.
Chelsea's situation is still very much in their own hands as they have still to play City and Spurs at Stamford Bridge, though they also have to travel to Old Trafford.
Their home record against United in recent years is strong having not lost since 2002 and, having had the weekend off, captain John Terry said his team were raring to go.
"We are very confident at home and the way they play might help us," Terry told the club's website.
"I'm not sure how they are going to come at us but other teams that have come to the Bridge have sat back and we've found it hard to break them down.
"It is a must-win game for us and the fans are going to be up for it. If we can win, who knows, it could put a little bit of pressure on them and the teams around us."
Although Chelsea had the weekend off they were still all over the newspapers after full-back Ashley Cole was reported to have shot a member of the club's staff with an air gun.
The club said they were treating it as an internal issue and would be taking "appropriate action" but that might not be the end of the matter as Surrey Police, who control the area where the incident took place at the club's Cobham training ground, said on Monday they would be investigating to see whether a criminal offence had taken place.
Ryan Giggs is likely to be fit for the match after recovering from a hamstring strain.
"It's always a big game at Chelsea," Sir Alex Ferguson told MUTV. "We used to have a great record down there but our record over the last seven years or so has been poor. We have to do something about that and that's what Tuesday is about."
