United were 2-1 winners against Leicester in their opening fixture but will be looking for a more convincing performance in their trip to Sussex.
Brighton crashed to a 2-0 defeat at Watford on Saturday and go into the home tie with United knowing a defeat would be a hard one to take, with a trip to high-flying Liverpool waiting for them next weekend.
Ahead of the meeting at the American Express Community Stadium, Goal takes a look at those who pose a risk to Mourinho's side.
Alireza Jahanbakhsh signed a five-year deal with Brighton having been a long-standing target for the seaside club.
“He can play in a wide position or central midfield attacking role, and I am now very much looking forward to working with him," Albion boss Hughton said upon his arrival.
Jahanbakhsh made his official Brighton debut in the club's season opener at Watford on Saturday, replacing Solly March deep into the 2-0 defeat.
The 25-year-old's time on the ball was limited at Vicarage Road but he is likely to play a more important role at the Amex on Sunday and the home support will be expecting a big performance from their record signing.
Anthony Knockaert's consistency, or lack of, has been discussed at length by spectators.
The diminutive forward has struggled to make his mark on the Premier League since Albion's promotion from the Championship in 2016-17, registering three goals and an assist in 33 league appearances last term.
Arguably Knockaert's strongest performance of the season last time out, however, came during Brighton's 1-0 win over United at the Amex in May, and a repeat display will be needed if his side is to get a result.
The Frenchman has the tenacity and the relentless energy to force this sluggish United side into trouble in a number of areas on the pitch and will be determined to lead his side to another upset.
Glenn Murray's no-frills approach to the game continues to pay dividends for the 34-year-old target man.
The former Crystal Palace striker has been Hughton's selected frontman in his favoured 4-4-1-1 formation since his return to Sussex and was the club's top scorer last season with 12 goals.
Though the Albion forward looked dead on his feet towards the end of the season, he will retain his spot at the head of his side's attack for at least the early stages of the season.
Murray will feel he has a point to prove with the likes of Tomer Hemed, Jurgen Locadia and Florin Andone waiting for the chance to replace him in the team, and he has the tools to punish United on Sunday.
Yves Bissouma is tasked with breaking up the tried and tested partnership of Dale Stephens and Davy Propper in the Brighton midfield but will be confident he has a major part to play on the south coast this season.
Signed from Lille in the summer, the Mali international made his Albion debut as a substitute against Watford and instantly perked up an otherwise limp Brighton side, replacing Pascal Gross as the creative hub behind Murray.
The 21-year-old immediately showed signs he could be a Premier League star, effortlessly gliding across the pitch whilst in possession, being successful in all four of his attempted dribbles and misplacing just a single pass in the 30 minutes he was afforded on the pitch.
Whether Bissouma eyes a permanent spot in an advanced midfield role in place of Albion's most creative outlet, Gross, or a slightly deeper position, he will certainly be aching to be handed an opportunity against United on Sunday.
Bissouma will be essential in his side breaking lines against United, with Hughton to continue his cautious approach against a remarkable midfield unit of Paul Pogba, Fred and Andreas Pereira.
Gross is far and away Brighton's most influential player and will be key to breaking down Mourinho's side on Sunday.
The German playmaker ranked highest in number of assists last season with eight, while averaging 2.5 key passes per 90 minutes. He also scored the winning strike against United in the aforementioned 1-0 victory at the Amex in May, completing his season tally of seven goals.
United will need to keep a close eye on Gross on Sunday as his distribution threatens to scupper their chances of victory at the Amex.
Leicester's persistence with attacking United with crosses - the Foxes attempted 27 to United's 12 on Friday - ultimately failed. However, it did exploit a number of holes in Mourinho's side which Claude Puel's men couldn't take advantage of.
Should Gross be given time on the ball on Sunday, Brighton will be confident of opening similar opportunities and securing at least a point from the fixture.