Erik ten Hag: “The start was not easy,” says Manchester United’s manager in an interview with the BBC. “I think the penalty was the turning point in the game. From that moment on, the game was all ours.”

On Matthijs de Ligt playing well: “I’m not surprised,” he says. “At this moment he is not fit, he’s not at 100% speed. He needs the games to go up to it. We see glimpses now and once he’s there he will do much better. We are happy with him and especially today with his game.”

On Marcus Rashford’s goal: “It’s very important. For every striker, they want to be on the scoring list. Once the first is in, more is coming. Once a striker was talking about a ketchup bottle: once it’s going, it’s coming more.”

On Manuel Ugarte: “He didn’t work with the team, it was two sessions, one before the break and yesterday. He was the only one later into the team training (after the international break) so only yesterday he had 20 minutes training with the team. We were happy we could bring him today and show what he could deliver to our team.”

Southampton 0-3 Manchester United

An email: “Given the significance of Onana’s penalty save in United going on to win so comfortably, should the goalkeeper be the player of the match even though he had pretty much nothing to do in the hour following that?” asks David Wall.

I can see where you’re coming from but the fact of the matter is that Cameron Archer’s penalty didn’t take much saving. It was really terrible, although I do appreciate Onana can only save the shot that’s fired at him, I don’t think he will begrudge Matthijs de Ligt the luminous yellow perspex cuboid he’s just been handed by TNT Sports touchline reporter Jules Breach.

Matthijs de Ligt: “Today we played really well although we had some trouble at the beginning,” he tells TNT SPorts. “It was a big credit to Andre (Onana) who saved a really important penalty. He changed the game for us.”

On his goal: “We’ve been working on some set-pieces and that one was not exactly out of the book but luckily I was in a good spot.”

Southampton 0-3 Manchester United

GOAL! Southampton 0-3 Man United (Garnacho 90+6)

90+3 min: We’re halfway through six minutes of added time. Southampton are on course to lose their fourth consecutive top flight game and only have one goal, against Brentford, on the credit side of the ledger so far. Manchester United win a corner but nothing comes of it.

90+1 min: Zirkzee has a shot from close range blocked by the right foot of Taylor Harwood-Bellis from about six yards out. He should have scored but dawdled over his shot after controlling a Dalot pull-back from the byline.

90 min: Garnacho tries to tee up Bruno Fernandes on the edge of the Southampton penalty area but the United captain is unable to sort his feet out in time to get a shot off. Adam Lallana clears.

87 min: Manchester United substitution: Matthijs De Ligt goes off with what looks like cramp and is replaced by Casemiro.

84 min: An exciting first half has been followed by something of a non-event of a second, in which a bamboozled fourth official trying to cope with a quadruple-substitution and the sending-off have been the highlights in terms of entertainment.

After showing so much promise before going behind once Cameron Archer had missed their penalty after 30 minutes, Southampton have been absoutley dismal. That spot-kick seems lik it was a real Sliding Doors moment.

82 min: Southampton have brought on Taylor Harwood-Bellis for Mateus Fernandes and the substitute slots in at centre-back in place of his recently departed skipper.

81 min: Russell Martin gets booked, presumably for protesting about the decision to issue Jack Stephens with a straight red. He can’t have any complaints.

Red card! Southampton down to 10 men

78 min: Man United substitution: Jonny Evans on for Martinez, who doesn’t want to be replaced despite his obvious discomfort.

76 min: Cornet gets on the ball out on the right wing and tries to cut inside, take on and beat Lisandro Martinez. The Argentinian, who is visibly struggling with an injury, is having none of it, stays on his feet and refuses to let him pass.

74 min: Manchester United triple-substitution: Harry Maguire, Alejandro Garnacho and Manuel Ugarte on for Noussair Mazraoui, Christian Eriksen and Marcus Rashford. Almost immediately, Maguire is booked for tapping the ball away Declan Rice-style to prevent Southamtpon taking a quick restart.

71 min: Maxwel Cornet is booked for failing to retreat 10 yards at a free-kick. I think we’ve had three cards dished out in this game so far, all of them for needlessly stupid offences bordering on the outright thick.

70 min: Both teams seem to be just going through the motions and the manner in which Southampton’s players appear to have hoisted the white flag of surrender since half-time will be a source of great concern to their fans.

68 min: Bruno Fernandes boots the ball away Joao Pedro-style after failing to keep it in play and is immediately booked for his troubles. He is not impressed and tells the referee he didn’t hear his whistle after the ball had gone out for a Southampton throw-in.

65 min: Ross Stewart makes his Premier League debut at centre-forward for Southampton. A £10m signing from Sunderland 20 months ago, the Scottish striker only made four substitute appearances for Saints last season, having arrived at St Mary’s with a torn achilles before doing his hamstring a serious mischief.

Southampton substitutions: Adam Lallana, Ross Stewart, Ryan Fraser and Maxwel Cornet on for Brereton Diaz, Archer, Dibling and Ugochukwu.

61 min: The corner comes in and the ball goes out off Downes, under pressure from Rashford. The match officials award a goal-kick.

60 min: Ramdsale leaps to palm the ball over the bar, in doing so preventing Marcus Rashford from scoring with a speculative effort from distance.

58 min: There’s a long way to go in this game but Southampton are already playing like a team that knows it is beaten. And well they might because Manchester United have never lost a Premier League game in which they have led 2-0 and have only drawn five out of 186.

56 min: A bit of a scramble on the edge of the Southampton six-yard box ends with a loose ball being hooked clear after Mazraoui had failed to pounce.

55 min: Sugawara is penalised for barging Marcus Rashford off the ball and pleads his innocence. Nothing comes of the free-kick wide on the left.

54 min: Ben Brereton Diaz boots a speculative ball from midfield into space behind the Manchester United defence but there’s nobody in a Southampton shirt on his wavelength or within 25 yards of the area in which the ball lands.

50 min: United sweep forward in numbers with Rashford on the ball. He takes on Bednarek and gets the ball on to his right foot before shooting high and wide. The ball takes a nick off Bednarek on its way out and United have another corner. Nothing comes of it as Ramsdale gathers Eriksen’s inswinger.

49 min: Mazraoui runs on to a pass in behind from Amad and tries to squeeze the ball home past Ramsdale at the near post. Wide. The United right-back’s reaction suggests he might have actually mis-hit an attempted cross.

48 min: Lisandro Martinez makes a crucial interception as Southampton try to play Dibling in behind down the right.

47 min: United enjoy a period of sustained possession before Ykinari Sugawara wins a throw-in for his side. Most of the early second half action is taking place in the middle third of the pitch, 20 yards either side of the halfway line.

Southampton 0-2 Man United

An email: “Dalot looks like an old, half-blind sheepdog trying to corral a young lamb that is giving him the runaround,” writes Justin Kavanagh of the roasting the Manchester United left-back has been getting from Tyler Dibling. “Will Ten Hag put him out of his misery at half-time like he did with Casimiro recently?”

Half-time: Southampton 0-2 Man United

45+1 min: Having played so well for long periods of this first half, things have gone massively pear-shaped for Southampton.

The positivity which permeated throughout St Mary’s as Cameron Archer stood over the ball hoping to put his side 1-0 up from the penalty spot 15 minutes ago has completely evaporated and it could be argued that the home side are now lucky to be only two goals down. It’s half-time.

43 min: Southampton are completely on the ropes. From another corner, the ball is played low into their penalty area and finds its way to an unmarked De Ligt. His shot from eight yards is superbly blocked by Aaron Ramsdale, who probably could have done better with his effort to save Rashford’s shot a couple of minutes previously. We’ll give him the benefit of the doubt and say he was unsighted …

GOAL! Southampton 0-2 Man United (Rashford 41)

41 min: Rashford, who has not scored since 17 March, is played in behind by Amad and finds himself one-on-one against Ramsdale. Southampton’s goalkeeper comes out on top and concedes another corner.

38 min: Moments before that goal and seconds after Southampton had missed their penalty, Joshua Zirkzee had brought a very smart save indeed out of Ramsdale, who got down well to tip his low shot around the post and concede the corner from which United scored.

37 min: United had a corner, which Christian Eriksen pulled short to Bruno Fernandes in acres of space near the left side of the Southampton penalty area. He had all the time in the world to pick out De Ligt at the far post and the Dutch defender made no mistake.

GOAL! Southampton 0-1 Man United (De Ligt 36)

34 min: Ben Brereton-Diaz looked ready to take the penalty but handed the ball to Cameron Archer. Perhaps that was the plan all along? After Archer placed the ball on the spot, he had a wait of almost a minute before Stuart Attwell gave him permission to take the penalty.

Onana saves Archer’s penalty!

Penalty for Southampton!

29 min: Amad gets on the ball and canters up the right flank before veering inside and unleashing a shot. The ball takes a big deflection off Jack Stephens before Aaron Ramsdale claims it.

28 min: A Yukinari Sugawara free-kick from the right near the byline is headed over the bar by a criminally unmarked Lesley Ugochukwu.