These teams have met four times this season, with Chelsea winning twice, losing once and drawing once. For what it's worth, both of those victories knocked United out of domestic tournaments, a fact that won't be lost on the Red Devils.
This game won't lack for fireworks, folks. Here's what Chelsea must do to earn the three points in a vital match.
Chelsea would be wise to be very aggressive early, as an early goal could take the Old Trafford crowd out of the proceedings. But the longer this game remains even—or if United take an early lead—the more enthusiastic the home crowd will be.
Technically, Manchester United have nothing to play for at this point in the season, but Chelsea did knock the Red Devils out of both the FA and Capital One Cups, so revenge may be in order. Plus, I'm sure United would love nothing more than to stick a wrench in Chelsea's top-four aspirations.
In other words, the Old Trafford crowd will find a reason to whip itself into a frenzy for an otherwise meaningless game for the home team. The more Chelsea can take the crowd out of the game, the better off they'll be.
Chelsea's Attackers Must Double Back Defensively
Chelsea are at their best when Juan Mata and Eden Hazard play on the wings and Oscar plays up the middle as an attacking midfielder. That trio is creative, capable of scoring goals and presents opposing teams with a lot to worry about.
But that trio also has a habit of collectively going lax on its defensive responsibilities. Against a team like United that is deadly on the counterattack and generally has strong wing play, a lack of commitment defensively from every player is akin to playing with fire.
I know Hazard and Mata want to be creative forces up the pitch, but they must pinch back on the wings when United move forward. Otherwise, the Red Devils will have far too much width to work with and will eventually crack Chelsea's defense and score.
Chelsea don't need to win this game to remain in the top four. With a mid-week game against Tottenham, Chelsea can still head into next weekend in third place if they lose to United but beat Tottenham. They will be in fourth place if they lose to United but tie Tottenham (on goal differential).
While a win would be clutch for the Blues, putting unnecessary pressure on themselves heading into Old Trafford isn't necessary. Sure, a win would put less pressure on the match with Spurs, but a tie or even a loss isn't the end of the world.
Win the Midfield
When Arsenal faced Manchester United last weekend, the Gunners absolutely bossed the midfield, controlling possession and limiting United's opportunities on goal. As a team, United doesn't have many weaknesses, but the weakest point is probably in the center of the pitch.
Which team wins?
Chelsea has had some turnover in those areas as well, but the deeper-laying pair of Ramires and John Mikel Obi have played effectively at times this season. Or, the versatile David Luiz may move up from his centre-back role and play in the midfield.
Whoever plays centrally, the team must take a page from Arsenal's approach and dominate that portion of the pitch. Along with dominating possession, that proved to be a very effective way of neutralizing the deadly United attack.