Manchester United’s hunt for trophies is over inside the second week of January after a ruthless Brighton took advantage of yet another loose defensive performance. This FA Cup third-round knockout means the 13-times winners have been dumped from the competition and the League Cup at the first opportunity for a first time since 1981-82.

By the end of May United’s season will stand at a total of 40 games – their lowest number in a complete campaign since 1914-15. If August’s Carabao Cup penalty shootout elimination at Grimsby was dire, this disappointment was as concerningly insipid, goals from Brajan Gruda and Danny Welbeck, one in each half, (probably) ending Darren Fletcher’s record as the interim manager as winless – this defeat following Wednesday’s draw at Burnley in the Premier League.

Thirty-one ties down, one to go. That’s Liverpool v Barnsley tomorrow, after which the draw for the fourth will take placee.

Brajan Gruda’s reaction

I’m very happy – it’s the first time I have won at Old Trafford. We had a good day, we really enjoyed it and I can see the fans enjoyed it as well!

Steeley dominated the game and we’re very happy to have him in goal.

The belief is always there. Everyone believes in each other and we can achieve anything.

The final whistle brings first boos and then an eerie silence at Old Trafford. United didn’t play terribly, in truth, but Brighton were more clinical and ultimately deserved their victory. Brajan Gruda put them ahead in the first half, then set up a superb second for the United old boy Danny Welbeck.

Benjamin Sesko gave United hope with a late header before the teenage substitute Shea Lacey – who enlivened the game when he came on – was sent off for two yellow cards.

90+4 min Ninety seconds remaining, give or take.

90+3 min Maguire and Kostoulas are booked for some nonsense.

90+2 min: Brighton substitution There will be five minutes of added time. Tom Watson has just come on for Brajan Gruda.

87 min Lacey overruns the ball and then takes out Ayari, a poor challenge for which he is booked. It was overzealous rather than malicious but he led with his studs; it might have been one for VAR were this a Premier League game.

84 min: Brighton substitution Charalampos Kostoulas replaces Georginio Rutter.

83 min This is one of those games, as the cliche goes, that has been decided in both boxes. United have probably been the better team in the middle third but that’s not much good to anybody when you’re 2-0 down. Brighton have been more ruthless, a quality we usually expect of the bigger club in FA Cup ties.

82 min This is United’s best spell of the second half. That’s not saying much, admittedly, but if they can find a goal it’ll set up a testosterone-fuelled finale.

81 min A crisp chest-volley from Sesko on the edge of the area is too close to Steele.

80 min Casemiro drags the ball deliberately into the path of Lacey, who lofts a curling shot on the run from the edge of the area. It ripples the roof of the net but it’s another sign of Lacey’s imagination and confidence; he looks one to watch.

79 min: Double substitution for Man Utd Maybe not. Harry Maguire and Casemiro replace Lisandro Martinez and Manuel Ugarte. This is Maguire’s first appearance since early November.

78 min Brighton have switched to a back three, it says here. Maybe it was a pre-emptive change because Harry Maguire is about to come on, possibly as a striker.

77 min: Triple substitution for Brighton Kaoru Mitoma, Jan Paul ven Hecke and Yasin Ayari replace Diego Gomez, Joel Veltman and Danny Welbeck, who loves scoring an FA Cup goal at Old Trafford.

76 min It looks like Man Utd are going to join a list of big clubs who have already gone out of the FA Cup: Crystal Palace, Tottenham, Everton, Nottm Forest, Bournemouth.

74 min Fernandes’s cross is headed up in the air at the far post. Dorgu launches into an eye-catching scissor kick but the ball bounces straight into Steele’s arm.

74 min Kadioglu hoofs over the bar from distance.

73 min The teenage substitute Lacey looks lively and fearless, and you know when he’s on the ball because that’s the only time the home crowd are getting excited at the moment.

71 min This would be Brighton’s first win over Man Utd in the FA Cup, and their fourth in the last five visits to Old Trafford.

Since you asked, the last time United went out in the third round of this competition was under David Moyes in 2013-14. They lost at home to Swansea on that occasion.

70 min “I know it’s between The Baby-Faced Assassin and Michael Carrick to get the job,” writes Peadar De Burca, “but don’t United only win the league with a Scottish manager?”

Are you suggesting they’re still in this season’s title race?

69 min Excellent play from Lacey, who beats Rutter and lifts a cross towards Sesko near the penalty spot. His downward header bounces a few yards wide of the far post. It was a pretty good effort as he had to move away from goal to meet the cross.

67 min It’s very quiet at Old Trafford now. Defeat today doesn’t mean United’s season is over, as there are European places to play for, but it would mean another season without a trophy.

Brighton cut United apart with two passes. Veltman, near the halfway line on the right, clipped a sharp pass into Gruda, who had taken up a good position between Dorgu and Martinez 30 yards from goal. Gruda turned and slipped an angled pass to Welbeck, who veered away from Yoro on the edge of the area and arrowed a left-foot shot into the roof of the net. The defending wasn’t great – that’s being kind – but it was such a clean, clinical move from Brighton.

62 min: Double substitution for Man Utd Joshua Zirkzee and Shea Lacey replace Kobbie Mainoo and Mason Mount. Fernandes will drop a bit deeper.

60 min Mainoo, who has had a fairly quiet game on his return, is booked for a foul on Welbeck.

60 min This is a good spell for Brighton, who are dominating possession and defending without recourse to the seat of their pants. United may need to change something. They could do with a young Darren Fletcher to up the intensity and drive the team forward.

58 min Gruda’s shot takes a deflection and goes behind for… a goalkick. The referees can’t get everything right.

55 min Man Utd are starting to show the first signs of frustration. Despite some bright attacking play, they still haven’t created a really clear chance since Dalot was denied by Steele in the second minute.

54 min The impressive Gruda skips down the right wing and is fouled. His low free-kick is inadvertently diverted across the area by Fernandes and spanked over by Veltman. Not a bad chance.

51 min A dangerous Brighton break is thwarted when Yoro makes an important challenge in his own area. Not sure who the Brighton player was, Gross possibly.

50 min “I’m watching the Brighton match in a bar in Malaga and greatly enjoying dual-screening it with your MBM,” writes Greg Wood. “Thought I should say tho in the interests of accuracy that I think it was Peter Jones who uttered the immortal line on the radio?”

Of course it was! Urgh, eejit. “… but he hasn’t scored”.

48 min The irrepressible Cunha makes a good run behind the defence on the left and wins a corner for United. Fernande takes, Welbeck heads clear.

46 min Darren Fletcher encourages the crowd to make some noise as he walks down the touchline ahead of the second half. Bruno Fernandes gets the match back under way.

Half-time reading

My Guardian colleague Tim de Lisle writes some of the most interesting, original and eloquent pieces about matters at Old Trafford. Here’s a flavour:

• Why Ruben Amorim was lucky to last so long

• What has already improved under Darren Fletcher

We need intelligent, mature sports writing more than ever, so please have a look.

45+1 min A nice effomrt from Cunha, who slips Veltman on the edge of the area, gives Steele the eyes and tries to reverse the ball inside the near post. It rolls a couple of yards wide, though I think Steele had it covered.

45 min A few grumbles from the crowd as a backheel from Dalot goes astray in the penalty area. He did very well to control a lofted pass on the run, having got the wrong side of Kadioglu, but the angle was tight for a shot so he decided to try to find a teammate.

41 min Fernandes hits a deliberate daisy-cutter under the wall. Nice idea but a few yards wide.

40 min Sesko is fouled 25 yards from goal by Veltman.

40 min Welbeck runs onto a return pass and hits the side netting from a very tight angle. Lammens gave him nothing to aim at.

39 min This is the quietest spell of what has been an entertaining first half. Brighton’s reserve centre-backs, Coppola and Boscagli, are doing a fine job.

37 min “The 1983 match between Man Utd and Brighton was the first live English football match I, as a football-starved emigre to Canada, was able to watch,” writes Allan Castle. “And it wasn’t broadcast live in Canada: it was only through the quirk of me working off the books in Singapore for the summer as an 18-year-old that I was able to see it.

“My abiding memories are many: the first time I ever heard John Motson (forever the voice of the FA Cup for me), astonishment at the heaving seas of supporters with homemade banners, Norman Whiteside, and above all Steve Foster, his white headband — and his tragic arc, from being banned for the final which must’ve been seriously crushing, to the gods deciding there must be a replay, to returning to the side but getting stuffed 4-0.

“I moved to North London a few years later and became an Arsenal fan for my sins, but have always had a soft spot for Brighton since those days in May.”

Motson is famous for ‘And Smith must score…’ at the end of extra-time but his commentary for Ray Wilkins’ goal is equally good.

33 min Dorgu plays a penetrative pass to the underlapping Martinez, whose cross/shot from a tight angle is blocked by the outrushing Steele. Good goalkeeper.

30 min Man Utd have had a good spell in the last 7-8 minutes, pinning Brighton back and playing at a pretty good tempo. But they do look vulnerable when Brighton counter attack. It’s a really fun, open game.

27 min Mainoo plays a simple pass into the area to Martinez, who rides a challenge and hammers a low shot that is crucially blocked by Boscagli.

25 min … it’s another deep corner that is half cleared a Brighton defender. It’s headed back into the six-yard box but the stretching Sesko can’t reach the ball and it drifts behind for a goalkick.

25 min Cunha moves over to the right, skips past Kadioglu and curls a dangerous cross that is sliced over his own bar by Coppola. Martinez is over the corner…

22 min A Brighton free-kick is headed away to Veltman, who shoots well wide from 25 yards.

21 min Mainoo waves a deep cross from the left that is headed wide by the backpedalling Cunha.

17 min Now Cunha shoots over the bar from 25 yards after controlling Fernandes’s pass deftly on the run. This is a really fun game.

16 min Sesko makes a well-time run behind the defence to receive a straight pass from Martinez. He tries to lob Steele on the run but doesn’t get enough on it and Steele makes a comfortable save.

Kadioglu moved through the inside-left channel and found Welbeck in the area. He lost Mount too easily with a swing of the hips and clipped a dangerous cross that was headed towards goal by Rutter. Martinez cleared off the line and Gruda slammed the rebound into the net.

8 min The resulting corner is swung beyond the far post by Martinez and headed wide by Yoro. A tough chance in a very crowded six-yard box.

7 min Man Utd have made an excellent start. Fernandes works a short frtee-kick with Mainoo and whips a shot towards the far corner from 25 yards. It takes a slight deflection and is scrambled round the post by the diving Steele. That’s another pretty good save.

3 min Moments later, Dalot blooters over the bar from the edge of the area.

2 min Man Utd have started with Mount on the right and Cunha on the left, though you’d imagine they will swap places from time to time.

1 min Brighton kick off from right to left as we watch.

The players walk on an icy afternoon in Manchester. Darren Fletcher, managing United at Old Trafford for the first time, makes an understated entrance – no eye-catching outfits or grand gestures, just applause to the fans as he walks down the touchline.

Gabriel Martinelli’s hat-trick gave Arsenal a 4-1 win at Portsmouth in their third round tie. Daniel Harris was watching that game.

It is hard for anyone much under 40 to grasp how important the FA Cup final used to be, how simultaneously desirable going to the Wembley showpiece was to an English football fanatic growing up in the 1970s and 80s. One of only two matches you knew would be televised live (along with England v Scotland), it overshadowed league football in a way unthinkable today.

In 1983, aged 15, I travelled to watch the final at the home of a Manchester United-supporting friend who lived at the far end of the London Underground line that runs through Wembley. Neither my friend Simon nor I settled down to watch United play Brighton with any thought of what might happen next.

Ole Gunnar Solskjær has had face-to-face talks with Manchester United regarding becoming the interim manager until the end of the season.

The Norwegian is vying with Michael Carrick for the role and wass expected to meet Omar Berrada, United’s chief executive, and Jason Wilcox, the director of football, at the club’s Carrington training base on Saturday.

Carrick is thought to have been interviewed on Thursday by Berrada and Wilcox. While the former United midfielder and Solskjær are the favourites, the current caretaker manager, Darren Fletcher, cannot be completely ruled out. The Scot oversaw United’s 2-2 draw at Burnley on Wednesday and will again take charge of Sunday’s FA Cup tie against Brighton at Old Trafford.