Albion suffered only their second away Premier League defeat of the season and lost Lewis Dunk to a straight red as they went down 2-0 to Manchester United at Old Trafford.
Cristiano Ronaldo ended his six-match goal drought with a goal five minutes into the second half and moments later Dunk was shown a straight red for bringing down Anthony Elanga.
It was harsh on Albion who had dominated the first half, with Jakub Moder forcing David De Gea to make a fantastic save to keep out his header.
United had chances to put the game to bed against the ten men but Moder went close again to breaking his goalscoring duck with a curling effort 13 minutes from time which beat De Gea but came back off the bar. Danny Welbeck headed over before Bruno Fernandes broke clear to make it 2-0 in the final minute of stoppage time.
It was another good performance by Graham Potter’s side but Ronaldo’s brilliance and the controversial red card tilted the contest United’s way.
Full of confidence after their seven-game unbeaten run, Albion had quickly settled into their rhythm and Moder had an early effort from a tight angle blocked by De Gea after Pascal Gross took advantage when Fred gave the ball away to find his fellow midfielder.
Neat and tidy in possession, Albion were relishing the occasion and Gross was involved again in the 17th minute after patient build-up down the right. The German picked out Alexis Mac Allister in space 15 yards out and although De Gea had to save it was probably an easier stop than he expected from the Argentinian’s scuffed effort.
The two chances United created in the first 30 minutes both came after Brighton gave the ball away. Adam Webster’s mis-control set Ronaldo away and his clever back heel found Jadon Sancho. Rob Sanchez blocked his first shot and Dunk acrobatically hooked the follow-up over the bar.
Marc Cucurella then got back to dispossess Anthony Elenga in the six-yard box when he shaped to shoot after Bruno Fernandes had instigated a United counter.
Gross fired wide after another good move as the Old Trafford crowd grew increasingly impatient – and 1200 Albion voices grew louder and louder.
They would have been celebrating but for De Gea’s brilliance in the 38th minute. Joel Veltman’s cross from the right picked out Moder’s run and his header was heading for the top corner until De Gea sprung to his right and tipped it over. A world class save.
Moments later Albion were in again down the right as Mac Allister played in the unmarked Yves Bissouma, whose low drive was a yard wide of the far post. Albion went off at the break disappointed not to be in front.
The game changed in a two-minute spell shortly after the break. United went in front in the 50th minute when Bissouma was dispossessed by Scott McTominay and the ball broke kindly to Ronaldo, who ran at a retreating defence before beating Sanchez with a powerful low shot into the bottom corner.
It got worse for Albion. Elanga nicked the ball off Dunk’s toes and the skipper brought him down. Webster appeared to be in a position to cover and referee Peter Bankes initially booked Dunk, but after VAR official Jarred Gillett intervened Dunk was shown a straight red.
Albion brought on Tariq Lamptey and Steven Alzate but United were now in the ascendancy and Sanchez produced a wonderful tip-over in the 66th minute to keep out Ronaldo’s close-range header after Fernandes found him with a dink to the far post.
Five minutes later Sanchez made amends with a good save from Fernandes’ shot, having initially given the ball away to Ronaldo inside the box before Moder was left shaking his head in frustration for the second time in the 77th minute.
After winning the ball on the left he looked up and unleashed a dipping effort which beat De Gea but came back off the crossbar. Then in the final minute of normal time Welbeck rose unchallenged to meet Lamptey’s cross but headed over from inside the six-yard box.
That was the chance and Albion were unlucky to concede a second with virtually the last kick. Mac Allister appeared to have been fouled deep inside United territory but the referee waved play on and Fernandes advanced before beating Sanchez from close range.
The second goal was harsh on the visitors, who could easily have left Old Trafford with some reward for their efforts.
Albion: Sanchez, Veltman, Dunk, Webster, Cucurella, Gross (Alzate 60), Bissouma, Moder, Mac Allister, Trossard (Lamptey 60), Maupay (Welbeck 70).
Subs: Steele, Lallana, March, Duffy, Caicedo, Ferguson.
Referee: Peter Bankes