Both teams need three points for different reasons
United head into the game after an energy draining 0-0 draw against Manchester City on Thursday evening at the Etihad Stadium which kept them in fifth place in the league table but they can temporarily go into the top four with a win against the Swans.
It won't be an easy task, though, as the Swans are also in desperate need of points as they currently sit 18th in the table, two points from safety, even though they defeated Stoke City 2-0 at home last weekend to give themselves a chance going into the final few games of the season.
The reason for them having a chance is due to the way Paul Clement has got the team playing since taking over as manager, overseeing his side win 3-2 at Anfield against Liverpool, but even he knows his side still need a few more wins to stay in the league.
United ran out comfortable winners earlier in the season
Mourinho will be hoping that the game goes the same away as the game did back in November when United won the game 3-1 at the Liberty Stadium.
Paul Pogba scored the opener for the Red Devils while Zlatan Ibrahimović scored the other two but both will not be playing when the sides meet on Sunday.
Mike van der Hoorn got a goal back for the Swans in the second half but on the day they were completely outplayed by United and will be hoping to show more fight this time around.
United's home form has a been a cause for concern this season
Something that will give the visitors some hope though is the fact that United have only registered seven wins in 17 home league games this season but they have only lost the game to their Manchester rivals back in September.
Mourinho only has 14 fit first team players going into the game after Timothy Fosu-Mensah and Marouane Fellaini were added to the list of United players who are currently unable to play. Fellaini will start his three-game suspension after receiving a straight red card for a headbutt on Sergio Aguero in midweek while Fosu-Mensah broke his collarbone in the final minutes of the game.
These two players join players such as Pogba, Ibrahimović, Marcos Rojo, Juan Mata, Chris Smalling and Phil Jones on the sidelines which just shows how much of a problem Mourinho currently has to pick his starting eleven.
Clement also has a few injury concerns to deal with before the game as he will be without Wayne Routledge, Angel Rangel and Nathan Dyer, who remain on the sidelines injured. Martin Olsson and Jack Cork will also have fitness tests before the game after they both missed the win against Stoke City last weekend.
The good news though is that top-scorer Fernando Llorente should be fit enough to start the game after recovering from injury while Gylfi Sigurdsson is looking to become only the fourth player in history to score in three consecutive away games at old Trafford.
Referee: Neil Swarbrick.