Match ends, Manchester United 3, Southampton 2.
Ole Gunnar Solskjaer says it was "like the old days" as Manchester United scored a late winner against Southampton to move three points behind third-placed Tottenham.
With United two minutes from missing out on fourth spot, Romelu Lukaku struck with a calm finish to settle a pulsating game at Old Trafford.
Lukaku celebrated by taking off his shirt after sealing a 10th win in 12 Premier League games under interim boss Solskjaer.
"I'm so pleased for the boys that they managed to claw three points out of this game," said Solskjaer, who famously scored a 93rd-minute winner for United in the 1999 Champions League final.
"The manner of it is like the old days. I have been part of it so many times myself."
|Race for the Premier League top four|
|3 March Fulham (A)|
|10 March Man Utd (H)||10 March Wolves (H)||10 March Arsenal (A)||9 March Southampton (A)|
|17 March Everton (A)|
|1 April Newcastle (H)||31 March Cardiff (A)||30 March Watford (H)||31 March Liverpool (A)|
|2 April Wolves (A)|
|7 April Everton (A)||8 April West Ham (H)||7 April Brighton (H)|
|15 April Watford (A)||14 April Liverpool (A)||13 April West Ham (H)||13 April Huddersfield (H)|
|20 April Crystal Palace (H)||22 April Burnley (H)||21 April Everton (A)||20 April Manchester City (A)|
|24 April Man City (H)|
|29 April Leicester (A)||28 April Man Utd (A)||28 April Chelsea (H)||27 April West Ham (H)|
|4 May Brighton (H)||4 May Watford (H)||4 May Huddersfield (A)||4 May Bournemouth (A)|
|12 May Burnley (A)||12 May Leicester (A)||12 May Cardiff (H)||12 May Everton (H)|
|Wolves (A) Date TBC||Brighton (H) Date TBC||Crystal Palace (H) Date TBC|
Yan Valery had given struggling Saints a surprise lead with an outstanding finish from around 25 yards before United turned it around with two goals in six second-half minutes.
Andreas Pereira equalised with a spectacular long-range strike before setting up Lukaku to make it 2-1.
Saints fought back to make it 2-2 through James Ward-Prowse's exquisite free-kick before Lukaku's dramatic winner.
In an incident-packed match, Paul Pogba missed the chance to make it 4-2 when Angus Gunn saved his late penalty.
How long before United appoint Solskjaer?
When Solskjaer was appointed interim manager in December following Jose Mourinho's dismissal, third place looked a distant dream for United.
Yet since the Norwegian took charge, United have won at least five more Premier League points than any other side.
Having moved ahead of Arsenal in the table with victory over Southampton, United will extend their lead over the Gunners to four points with eight matches remaining if they beat Unai Emery's side in London on 10 March.
After falling behind to Valery's sensational strike, United struggled to get into any rhythm before Diogo Dalot's 52nd minute introduction for Alexis Sanchez, who looks to have suffered a suspected knee injury.
Pereira's curled finish was of the highest quality and Lukaku showed great composure to make it 2-1 with a low, controlled finish.
Yet United, who had failed to win their previous three home games, looked like they would have to settle for a point after Ward-Prowse's free-kick made it 2-2.
However, there is a never-say-die spirit about Solskjaer's United and Lukaku celebrated wildly after hitting the winner - the 113th Premier League goal of his career.
"He is a quality scorer," added Solskjaer when asked about the Belgium forward's two-goal contribution.
"We need to have him more in front of the goal. But he has done fantastic in his work rate, attitude, he loves scoring goals, he smiles every day, he does extra shooting in training."
There was still time for Pogba to miss from the penalty spot after Stuart Armstrong had fouled Marcus Rashford.
But even that failed to dampen the mood of the home fans, many of whom left Old Trafford asking: how long before United's hierarchy make Solskjaer's appointment permanent?
Can you name the top 20 Premier League scorers?
Positives in defeat for Saints
Southampton remain two points above the relegation zone after a third defeat in four games.
Yet there are reasons to be optimistic about their survival chances over the next nine games despite ending up with nothing from a battling performance.
While Valery's opening goal was sumptuous, Southampton's response to falling 2-1 behind shows there is character and spirit flowing through Ralph Hasenhuttl's side.
The Saints still have to play Tottenham and Liverpool but their run-in also includes home games against Huddersfield and Bournemouth.
In addition, they will feel confident about away games against Brighton, Newcastle and West Ham if they can put in the same level of commitment as they did against United.
When Hasenhuttl took charge in December, Southampton were one point from safety. Despite this result, they have 18 points from 14 games and staying up is very much in their own hands.
Man of the match - Andreas Pereira (Manchester United)
'We deserved more' - what they said
Southampton boss Ralph Hasenhuttl: "We deserved more. We played a fantastic game tactically. We showed we can play with the ball and pressed them.
"We didn't stop working. It doesn't feel good because we lost but it starts from 0-0 in our next match against Tottenham.
"It is not enough that we played for 60-70 minutes in a very good way against such a side."
'Solskjaer planning for next season'
Analysis: Former England captain Alan Shearer, speaking on Match of the Day
What a job Ole Gunnar Solskjaer is doing. Manchester United were 11 points off the top four when took he over and they've made that up.
It doesn't matter whether he gets the job next week or at the end of the season - he's getting it. Decisions are being made now behind the scenes for pre-season, players coming in and players going out.
He's making those decisions.
Comeback kings against Saints - the stats
- Manchester United have come from behind to win nine Premier League matches against Southampton, an outright record in the competition.
- Southampton are the first away team to score two goals from outside the box in a Premier League game at Old Trafford since Manchester City in September 2009.
- United striker Romelu Lukaku has been involved in 11 goals in his last 11 Premier League appearances against Southampton (9 goals, 2 assists).
- Andreas Pereira became the first Brazilian to score and assist in a Premier League game for Manchester United since Anderson in May 2011 v Blackpool.
- Southampton's James Ward-Prowse has scored five Premier League goals this season, more than in any other campaign in the competition.
Trailing 2-0 from the first leg, United are in need of another comeback win when they go to Paris St-Germain in the Champions League on Wednesday (20:00 GMT). The games don't get any easier for Southampton - it's Spurs at St Mary's next Saturday (15:00).
- 1De Gea
- 15PereiraSubstituted forFredat 82'minutes
- 6PogbaBooked at 90mins
- 7SánchezSubstituted forDalotat 52'minutes
- 10RashfordSubstituted forChongat 90+5'minutes
- 9LukakuBooked at 89mins
- 3YoshidaSubstituted forGallagherat 90'minutes
- 21BertrandBooked at 39mins
- 10AustinSubstituted forArmstrongat 63'minutes
- Stuart Attwell
- Shots on Target
Second Half ends, Manchester United 3, Southampton 2.
Paul Pogba (Manchester United) is shown the yellow card.
Tahith Chong (Manchester United) wins a free kick on the left wing.
Foul by Yan Valery (Southampton).
Substitution, Manchester United. Tahith Chong replaces Marcus Rashford.
Penalty saved! Paul Pogba (Manchester United) fails to capitalise on this great opportunity, right footed shot saved in the centre of the goal.
Penalty Manchester United. Marcus Rashford draws a foul in the penalty area.
Penalty conceded by Stuart Armstrong (Southampton) after a foul in the penalty area.
Substitution, Southampton. Sam Gallagher replaces Maya Yoshida.
Romelu Lukaku (Manchester United) is shown the yellow card for excessive celebration.
Goal! Manchester United 3, Southampton 2. Romelu Lukaku (Manchester United) right footed shot from outside the box to the bottom right corner.
Corner, Manchester United. Conceded by Yan Valery.
Attempt missed. Jannik Vestergaard (Southampton) right footed shot from the centre of the box misses to the right. Assisted by Pierre-Emile Højbjerg with a headed pass following a corner.
Corner, Southampton. Conceded by Chris Smalling.
Attempt blocked. Maya Yoshida (Southampton) header from the centre of the box is blocked. Assisted by Nathan Redmond with a cross.
Corner, Southampton. Conceded by Luke Shaw.
Corner, Southampton. Conceded by Victor Lindelöf.
Substitution, Manchester United. Fred replaces Andreas Pereira.
Foul by Paul Pogba (Manchester United).