It was a dull opening 45 minutes at Old Trafford, with the best chance coming from a Jakub Moder header that David De Gea did well to save.
But the second half was a different story, and Cristiano Ronaldo ended his six-game goal drought by hitting a powerful effort past Robert Sanchez on 51 minutes.
Soon after, Lewis Dunk was shown a red card for pulling back Anthony Elanga when in on goal, although it did take a pitch-side review at the monitor to come to the decision.
United were by far the better side in the second period and their dominance showed in injury-time as Bruno Fernandes rounded off a breakaway attack by feinting and then smashing the ball into the back of the net.
Manchester United player ratings
David De Gea- 6
Was called into action to make a great save from a Moder header after 38 minutes and he could do nothing when the Polish international cracked an effort off the United crossbar later in the night. There were some groans from the home fans at how long De Gea took over goal-kicks in the first half.
Diogo Dalot- 6
Advanced more in the second half and contributed to United’s attacks, especially with Brighton moving to 4-3-2 after the red card. Dalot’s long passes weren’t great, but it was a solid display from the defender.
Victor Lindelof- 7
Started in place of Raphael Varane, who pulled out through illness in the warm-up. The Swede was solid in possession and drove forward with the ball on a few occasions. He was a tad unfortunate to miss out on the man of the match award.
Harry Maguire- 7
Much better from the United captain after he was given reassurances in the week from Ralf Rangnick. Maguire often took the simple option on Tuesday and looked much more comfortable in possession. The defender even had a shot saved in the 81st minute.
Luke Shaw- 5
Again, looked more competent with the ball than when asked to defend. The left-back was caused a few issues by Moder in the first half.
Scott McTominay- 5
Set up Ronaldo’s goal with a strong tackle on Yves Bissouma, and McTominay’s best work came out of possession. The Scotland international struggled with the ball at his feet, although he was much better after the break. The No.39 also went down with a slight knock in the second half but managed to play on.
Bruno Fernandes- 7
Missed a one-on-one opportunity midway through the second half, and had a shot saved by Sanchez on 81 minutes. Fernandes’s influence grew as the game continued, and he provided two excellent crosses in the second half which were met by Ronaldo. He ended a great second half by finishing off a United counter-attack and placing the ball into the back of the visitors’ net. Despite the No.18’s first-half showing, he earned our Man of the Match.
Fred- 5 (off 73)
It wasn’t a great performance from the midfielder, who repeatedly gave the ball away. He helped United win possession on several occasions and pressed well, but the No.17’s substitution was greeted by a huge cheer from the Old Trafford faithful in the second half.
Anthony Elanga- 6 (off 79)
His work rate and closing down led to the Brighton red card and he helped United maintain their dominance after the break. However, the youth graduate failed to create many moments of clear quality.
Cristiano Ronaldo- 7
Ended his longest scoring drought since 2009 when he smashed the ball past Sanchez at the start of the second period, after a quiet opening 45 minutes. He also saw a header saved on 66 minutes and played in Fernandes for a one-on-one chance soon after. Tuesday was his best performance for a number of weeks.
Jadon Sancho- 7 (off 79)
Was United’s most lively player in the first half and went close with a breakaway chance. He wasn’t as effective after the break, but did create a dangerous opening after skipping beyond Joel Veltman in the wide areas. It was another good showing from the in-form wideman.
Paul Pogba- 7 (on 73)
Brilliant in possession and displayed several cute turns and bits of skill. It was an excellent cameo from the midfielder, who helped United keep the ball in the latter stages. His quick thinking also set up Fernandes’s late second.
Marcus Rashford- 6 (on 79)
Didn’t have much time to make an impact, but did produce one dangerous dribble.
Alex Telles- 6 (on 79)
Added more defensive discipline down the left and had a shot deflected wide off Tariq Lamptey.
Brighton & Hove Albion player ratings
Sanchez 5; Veltman 6, Dunk 4 (off 54), Webster 5, Cucurella 6; Bissouma 6, Gross 6 (Alzate 60; 5), MacAllister 5; Moder 7, Maupay 6 (Welbeck 70; 6), Trossard 5 (Lamptey 60;7).