It is the second consecutive campaign Saints have suffered a 9-0 thrashing after Leicester last season at St Mary’s equalled the record set by United against Ipswich in 1995.
The visitors were punished for Alexandre Jankewitz‘s second-minute red card on his Premier League debut.
Today’s to-do list:▪️ Equal our all-time biggest #PL win ✅ End of list. https://t.co/JGSCLy0dk1
— Manchester United (@ManUtd) 1612304926000
Aaron Wan-Bissaka, Marcus Rashford, Edinson Cavani and Jan Bednarek‘s own goal made it 4-0 before half-time.
Anthony Martial came off the bench to score twice in the second half, while Scott McTominay, Bruno Fernandes and Daniel James also netted either side of Bednarek’s late dismissal.
City have two games in hand on United to reassert their advantage in the title race, the first of which comes at Burnley on Wednesday.
But United boss Ole Gunnar Solskjaer evoked memories of the 2011/12 title race that City snatched on goal difference from their local rivals as the reason why his side had to show no mercy.
“We know better than anyone what goal difference can do to you because we have lost the league on goal difference,” said the Norwegian.
Solskjaer had called on his forward players to be more clinical after a number of missed chances cost United in a shock 2-1 defeat to Sheffield United and 0-0 draw at Arsenal over the past week.
Rashford, Martial and Fernandes had all seen goals dry up in 2021, but Solskjaer is hoping they will now have the perfect confidence boost heading into the second half of the season.
“We’ve been waiting for them to show the magic and it was a night for them to go and enjoy it,” he added. “We’ve not had many times where we could just enjoy the second half.”
Ralph Hasenhuttl survived the 9-0 thrashing by Leicester to turn his time in charge of Southampton around.
But after a bright start to the season, the Saints have lost four consecutive leagues games to slip to 12th.
Southampton were already decimated by an injury crisis that led to Jankewitz getting his chance before the 19-year-old lunged into McTominay after just 79 seconds.
“He punished the guys who were on the pitch. They were helpless after he is sent off,” said Hasenhuttl.
“You know the 90 minutes can be very long against a team of this quality. The result is there and we have to live with the result again.
“It doesn’t reflect what we did this season so far. It’s hard to explain. We have to live with this again.”
Wan-Bissaka opened the floodgates on 18 minutes when he scored just his second goal for the club by meeting Luke Shaw’s cross at the back post.
Rashford then converted Mason Greenwood’s cross and it was from his driven low ball across the box that Bednarek turned into his own net.
Cavani powered home a header from another Shaw cross before the Uruguayan thought he had won a penalty.
A VAR review gave Southampton a rare let-off as instead a free-kick on the edge of the box was awarded.
However, Hasenhuttl’s men were denied themselves after the break when Che Adams had a consolation strike ruled out for a marginal offside.
The goals at the other end kept on coming as Martial ended his eight-game goal drought with a thumping finish from Fernandes’s through ball.
McTominay then drilled home a low effort from long range.
A nightmare night for the visitors continued when Bednarek was harshly sent off after another lengthy VAR review for clipping Martial as he bore down on goal.
Fernandes coolly converted the resulting penalty to end his own five-game goalless run in the league.
Martial then controlled and finished Wan-Bissaka’s cross before James inflicted the final blow in stoppage time by flicking home Fernandes’s header.