The Red Devils are still smarting after finishing a distant second to their city rivals in the league, and will be hoping ex-Blues manager Jose Mourinho can get one over on his former club.
Chelsea desperately need to end the season on a high after missing out on Champions League football and will be determined to lift a trophy in what could be Antonio Conte's last game at the club.
With world class talent on both sides, it promises to be a closely fought encounter. Here are four key battles that could decide Saturday's Wembley showpiece:
4. Eden Hazard vs. Antonio Valencia
Despite a disappointing season for his club overall, Eden Hazard has emerged largely unscathed, showing flashes of his potentially world class talent which has led to rumours he could swap west London for the Bernabeu this summer.
Before that, he must get past Antonio Valencia, whose brilliant form this season has made him one of Jose Mourinho's most trusted players. If the Belgian can evade the Ecuadorian, it could be a long afternoon for the United defence.
3. Alexis Sanchez vs. Victor Moses
With the Chilean finally showing signs of his best form after a slow start since his January move from Arsenal, he will be one of the Red Devils' key attacking threats if they are to be celebrating at full time.
Having been man of the match in the semi final against Spurs, Sanchez is a proven big game player and will be invaluable on Saturday, having scored at Wembley last year in Arsenal's 2-1 win over the Blues. Victor Moses, sent off in last year's final, will be tasked with stopping him and should provide a fierce matchup.
2. Olivier Giroud vs. Chris Smalling
Olivier Giroud has hit good form towards the end of the season and may be preferred to the inconsistent Alvaro Morata to start in Saturday's final. The Frenchman won three FA Cups in four years with the Gunners and has a good record at Wembley, having opened the scoring in this year's semi final.
Chris Smalling will be disappointed to have been left out of Gareth Southgate's squad this week, but will be itching to end the season on a high by helping his team lift the FA Cup.
1. Paul Pogba vs N'Golo Kante
With Paul Pogba underwhelming since his club record return from Juventus two years ago, this is tailor made for the Frenchman to step up and carry his side to the trophy weeks before he heads to the World Cup with France.
If Jose Mourinho lets the 25-year-old roam freely on the pitch, he possesses the quality to control the game and win the Cup, although he will have to contend with Chelsea's brick wall in compatriot N'Golo Kante.
On his day, Pogba is a world class box-to-box midfielder, but Kante will be stern opposition if United are to win the game.