Around mid-season, many had written off this fixture as a title-decider. At the time, Chelsea were bang down in the middle of their slump, whilst Manchester United were leading them by a seemingly unassailable 15 points.
How times have changed? After Man United's defeat last week to Arsenal at the Emirates, Chelsea suddenly re-entered the frame, realistic contenders for the title glory, when just a couple of weeks back people looked upon Arsenal to provide the main threat to United's title surge.
The last time the two sides met this season, it was in the Champions League quarterfinals. United had the upper hand then, ousting Chelsea from the competition they craved the most with an aggregate 3-1 win. They were deserved winners too. Coming on the back of a 1-0 win at Stamford Bridge, they held their nerves to score a late winner as the match finished 2-1 in the return leg. For Chelsea, it was tie in which many predicted the end of the Ancelotti era, mainly due to the Italian's decision to pick expensive January signing Fernando Torres over the bulldozer that is Didier Drogba.
Ancelotti would have learned a lot from that tie and is unlikely to make the same mistake. He would do well to start with Drogba, and accommodate Torres late in the game as an impact substitute.
Unlike Torres, Chelsea's other January signing - David Luiz - has hit the ground running and has captured the affection of both of players and fans. So much that, skipper John Terry was recently quoted as touting him as a future captain of the Blues. Luiz played an instrumental role in Chelsea's 2-1 league win over United in March, scoring a crucial goal before managing to stay on field despite committing bookable fouls while already on a yellow card. His form has since failed to match his initial heights though, but his battle against Javier Hernandez - a contender for the 'signing of the season' award - could go a long way to deciding this tie.
However, there is no denying the magnitude of what Terry and co. are attempting to do. United have lost just two points at home all season, in a draw with West Brom. Though Chelsea have won their last three league encounters against United, the Red devils, inevitably, raise their game when they play at their fortress.
A shoddy away form has been United's undoing this season, and had they picked up a few more points on the road, they would have wrapped the title long back. A draw at Newcastle before last week's loss at Arsenal, coupled with Chelsea's magnificent run in which they took 25 off 27 available points, put the Blues back in the title front.
The task is simple for Chelsea - win at any cost. United will look upon a draw as a satisfactory result as it will give them a three point lead with only two games left.
The game will be far from a classic as far as the purists, who love nothing more than seeing the passing game, are concerned. However, given the pressure, hype and what is at stake, the game's already a classic, even before it has begun. World cup final referee Howard Webb has been handed the task of monitoring the tie. And he will have quite a job of it. Players will lose their heads, while he has to ensure he keeps his.
The stage is set.