By SABC Sport
8th April 2023
The Norwegian came back into City's line-up after recovering from a groin problem and headed the visitors in front shortly before the break from Kevin De Bruyne's cross.
Jack Grealish scored a second on the hour after his initial effort had been saved by Saints goalkeeper Gavin Bazunu.
Haaland produced an acrobatic finish to score City's third in the 68th minute which took his tally to 30 league goals.
Southampton pulled a goal back from substitute Sekou Mara with 18 minutes left but City quickly scored again through a penalty from Julian Alvarez, who had come on to replace Haaland, following Kyle Walker-Peters' foul on De Bruyne.
Arsenal will be looking to re-establish their eight-point cushion when they travel to Liverpool on Sunday.
Earlier, Frank Lampard's return as Chelsea manager ended in a 1-0 defeat to relegation-threatened Wolves at Molineux.
Matheus Nunes scored the winner after 31 minutes, the Portugal midfielder's first goal for Wolves since his club-record move from Sporting Lisbon in August.
Despite the return of Stamford Bridge hero Lampard following the sacking of Graham Potter, Chelsea failed to score for the third successive game.
The Blues remain 11th after just two wins in 11 league games and Lampard must raise the players ahead of this week's Champions League quarter-final first leg against holders Real Madrid.
Newcastle stay third after coming from behind to beat Brentford 2-1 in west London.
The Bees went ahead after Ivan Toney, who had earlier seen his tame penalty saved by Nick Pope, scored from the spot on the stroke of half-time against his former team.
After Bees goalkeeper David Raya diverted Joelinton's ball across goal in to his own net after 54 minutes, Alexander Isak scored a fantastic decider just after the hour mark to secure Newcastle's fifth successive victory.
Manchester United maintained their top-four push with a 2-0 home win over Everton.
Scott McTominay broke the deadlock after 36 minutes after Antony had struck a post and United had missed a host of gilt-edged chances.
Substitute Anthony Martial's first Premier League goal of 2023 after 71 minutes wrapped up the win, although an injury to top scorer Marcus Rashford threatens to take the sheen off the three points.
Tottenham remain fifth - three points behind Newcastle and Manchester United while having played a game more than both of them - after beating Brighton 2-1.
Son Heung-min opened the scoring with his 100th Premier League goal, but Lewis Dunk levelled shortly after Kaoru Mitoma was ruled to have controlled with his upper arm before converting.
Harry Kane's winner 11 minutes from time kept Spurs in the mix for a Champions League place.
Aston Villa boosted their hopes of European football with a 2-0 home defeat of Nottingham Forest.
Bertrand Traore and Ollie Watkins, with his ninth goal in 11 games, scored as Forest dropped into the bottom three after yet another away day without reward.
Bournemouth climbed out of the bottom three as Philip Billing's cool first-half finish gave them a vital 1-0 victory at the expense of fellow strugglers Leicester.
Having sacked manager Brendan Rodgers last Sunday, Leicester are now in real danger of dropping into the Championship on the back of picking up just eight points since Christmas.
The Cherries are up to 15th and three points above the drop zone.
West Ham lifted the pressure on manager David Moyes as an own goal from Harrison Reed proved the difference at Craven Cottage.
After losing 5-1 at home to Newcastle on Wednesday, the Hammers recorded just their second away win of the campaign to move up to 13th, three points clear of the relegation zone.