Matthijs de Ligt, Marcus Rashford and Alejandro Garnacho scored to give Erik ten Hag a much-needed win at St Mary’s, but it wouldn’t be Manchester United if there wasn’t a scare somewhere along the way.

Andre Onana had to make a first-half penalty save from Cameron Archer as United’s early-season problems threatened to explode into a full-blown crisis on the South Coast against the newly-promoted Saints who have now lost all four of their opening Premier League games and also had captain Jack Stephens sent off for an awful challenge on substitute Garnacho towards the end.

United’s start had comprised of two defeats from three games and another here bordered on the unthinkable. Not since 1986 had the club lost three of the first four, leading to the sacking of Ron Atkinson and arrival of Sir Alex Ferguson.

Fortunately, Onana’s save from Archer was the wake-up call they needed to raise their game and go two up within another four minutes through De Ligt’s first goal for the club since signing from Bayern Munich and Rashford’s first in six months since the FA Cup quarter-final win over Liverpool at Old Trafford.

This result will take some of the early-season heat off Ten Hag whose next Premier League game is against Crystal Palace at Selhurst Park where a 4-0 defeat last season left his job hanging by a thread.

Marcus Rashford (left) and Matthijs de Ligt got the goals as Man United beat Southampton

De Ligt headed United into the lead in the 35th minute of the Premier League clash

Marcus Rashford (left) curled home the second from range to double the lead before the break

Rashford (right) celebrates after scoring his first goal for Manchester United in 189 days

The doubts have resurfaced this season sooner than anyone expected, but ultimately this was a good day ahead of Barnsley’s visit to Old Trafford in the Carabao Cup on Tuesday.

The big question coming into the game was whether Ten Hag would keep faith with Casemiro following his error-strewn display against Liverpool last time out or play new £50.5million signing Manuel Ugarte. The answer was neither. Both started on the bench alongside a third defensive midfielder, Toby Collyer, with Christian Eriksen partnering Kobbie Mainoo in the middle.

It was a bold move by the United boss but an opportunity he thought Eriksen deserved. ‘He has had a good pre-season and in training he’s had very good performances, so he has earned a start,’ said Ten Hag, who also started Amad Diallo on the right in place of Garnacho.

‘We have to integrate Manuel into the team. He has only had two sessions, we have to integrate and that takes time. Casmeiro will play, I am convinced of this. We have a squad and we offer a lot of games.

De Ligt (left) managed to turn his header past Aaron Ramsdale (right) and into the net

Ramsdale was also powerless to stop Rashford’s curling effort creeping in off the post

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On paper, this felt like a straightforward game for United sandwiched in between the difficult Premier Lague fixtures against Liverpool and Palace. Saints had not beaten United in the league in 14 games since 2016 and not at St Mary’s since 2003. They came into this game on a club record 16 Premier League games without a win after suffering three straight defeats since returning to the top-flight.

Saints boss Russell Martin gave a first league start to Lesley Ugochukwu, on loan from Chelsea, and young Tyler Dibling as he sought to end that run.

He might have managed it too, had the game not pivoted a different way during a decisive four-minute period towards the end of the first half.

Diogo Dalot, still playing on his weaker side at left-back in the absence of Luke Shaw and Tyrell Malacia, had been struggling with Dibling all game before the young livewire went past him again in the 37th minute. Dalot made a clumsy lunge to try and stop him but brought Dibling down and referee Stuart Atwell pointed straight to the spot.

Onana has made a couple of penalty saves in his first year at United and the Cameroonian came up trumps again, diving to his right to keep out Archer’s effort and then comfortably holding the striker’s follow-up header.

Alejandro Garnacho fired the ball into the roof of the net to wrap up the win in injury time

Garnacho celebrated his goal by sitting on the advertising board and crossing his arms

United punished Saints almost immediately. After Aaron Ramsdale turned Joshua Zirkzee’s low shot around the post in the 35th minute, Eriksen played a corner short to Bruno Fernandes. The United skipper curled a cross to the edge of the six-yard box where Stephens was playing a number of United players onside including De Ligt who steered a downward header inside the far post.

It was all the more sweet for De Ligt who came under fire for his performances for Holland during the international break, and was substituted at half-time against Germany on Tuesday.

United almost had a second when Ramsdale saved point-blank from Rashford after he exchanged passes with Amad, but the visitors – and Rashford – didn’t have to wait long.

The home side won a penalty when Diogo Dalot brought down Tyler Dibling in the area

Southampton’s Cameron Archer saw his spot-kick saved by United stopper Andre Onana

Eriksen again took the corner and play was switched to the left where Amad fed Rashford. He cut inside Archer and curled a shot inside Ramsdale’s left-hand post with the keeper partially unsighted by De Ligt.

Until then, Saints had more of the play in the opening half hour with United shading the better chances.

Dibling turned Dalot to race away and force a flying save out of Onana, and Ugochukwu headed narrowly over from a free kick.

At the other end, Zirkzee could have scored but wasn’t alive to Eriksen’s clever pass and couldn’t get enough on his lunging effort to trouble Ramsdale. Noussair Mazraoui tested the keeper with an ambitious volley from 25 yards and Fernandes shot wide from Amad’s pass on the breakaway.

Jack Stephens received a straight red card for a high flying challenge on Alejandro Garnacho

Stephens (right) seemed unhappy with the decision but he could have no complaints

De Ligt went close to his second and United’s third before half-time but Ramsdale came out to block, and did the same to deny Rashford shortly after the interval before tipping another curling effort from United’s No.10 over the bar.

Ten Hag’s side were attacking almost at will and should have extended their lead had they been more clinical. Martin responded by sending on four substitutes – Adam Lallana, Ross Stewart, Ryan Fraser and Maxwell Cornet – to try and drag Saints back into the game.

It made little difference and Ten Hag was able to send on Ugarte for Eriksen and Casemiro as auxiliary centre-back for De Ligt.

The Brazilian had a hand in United’s third goal in added time, splitting the defence so Dalot could square for Garnacho to crash a shot into the roof of the net.

Saints were down to 10 men by then after Stephens was shown a straight red in the 79th minute for an ugly touchline challenge on Garnacho which caught the Argentina winger on his right knee.

They have become the first side to lose their first four games in three different Premier League seasons. It’s a long way back from here.