Manchester United equalled a Premier League record for a winning margin as they ruthlessly battered nine-man Southampton 9-0 to go level with leaders Manchester City.
The contest was essentially decided after just 79 seconds as 18-year-old Alex Jankewitz, on his full Premier League debut, saw red for a high, horror tackle on Scott McTominay, prompting Saints to capitulate.
Two of United's first-half goals came from Luke Shaw's pinpoint left-wing deliveries - first, Aaron Wan-Bissaka turned home at the far post (18), before Marcus Rashford struck from 12 yards from Mason Greenwood's cut-back (25).
Rashford's dangerous ball was then turned into his own net by Jan Bednarek (34), and Edinson Cavani then got in on the act with a fine header into the far corner from another brilliant Shaw ball (39).
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Sub Anthony Martial got his first goal in eight appearances with a superb control and finish from a tight angle (69), while McTominay got in on the act with a controlled, long-range effort (71).
Bruno Fernandes scored a late penalty as Bednarek saw red for a last-man foul on Martial (88), then the France international got his second with a close-range effort (90), and Dan James rounded it off with a stoppage-time finish (90+3).
It's the second time Ralph Hasenhuttl has been on the wrong end of a 9-0 defeat in the Premier League with Saints, following their infamous defeat at the hands of Leicester last season. United last won a match by this margin in March 1995 vs Ipswich Town (9-0), and have now scored more goals than any Premier League side this season (46).
The result means United go level on points with Man City for 24 hours at least, having played two more games than their Manchester rivals, who go to Burnley on Wednesday evening. United are, however, four points ahead of Liverpool having played a game more, while Saints are 12th having lost their last four.
Man Utd: De Gea (7), Wan-Bissaka (8), Lindelof (7), Maguire (7), Shaw (9), Fred (7), McTominay (8), Fernandes (8), Rashford (8), Greenwood (7), Cavani (8)
Subs: Martial (8), Van de Beek (7), James (7)
Southampton: McCarthy (4), Ramsay (4), Stephens (4), Bednarek (3), Bertrand (4), Ward-Prowse (4), Jankewitz (1), Djenepo (4), Armstrong (4), Adams (5), Ings (4)
Subs: Redmond (5), Tchaptchet (NA)
Man of the match: Luke Shaw
How merciless Man Utd feasted on indisciplined Saints
Criticised for holding back in recent weeks in contests against bigger sides, United were merciless at Old Trafford with a statement victory, albeit handed to them on a plate by their opponents.
Injuries forced Saints to hand full Premier League debuts to youngsters Kayne Ramsay and Jankewitz, but the latter's day lasted barely two minutes as his shocking challenge on McTominay left Hasenhuttl in disbelief. Overeager and naïve, Jankewitz went in knee-high on the United midfielder on halfway, leaving Mike Dean with no choice.
At first it looked like United would have to work hard against what was essentially one bank of nine outfield Saints players, but once they got the first, the floodgates opened.
The in-form Shaw had the freedom of Manchester on the left, and curled in a beauty for Wan-Bissaka to tuck home at the far post, his second Premier League goal of the season having never scored in any of his three previous seasons.
Rashford got United's second, this time from Greenwood's assist; having darted to the byline, Greenwood found Rashford on the penalty spot, and he opened his body up before sweeping past Alex McCarthy.
James Ward-Prowse forced a good save out of David de Gea at the other end from a free-kick, but it was soon 3-0 as Rashford's wicked ball from the right was diverted into his own net by Bednarek as Fred lurked behind him ready to pounce.
Cavani got the fourth, heading home unmarked from 10 yards from another Shaw delivery from the left, and the Uruguayan thought he had won United a penalty in first-half stoppage time from Ramsay's challenge, but VAR adjudged the contact to be just outside the box despite Dean initially giving it.
Ole Gunnar Solskjaer brought off Cavani and Rashford at half-time, and although United slowed down at first - Che Adams had a goal ruled out for offside by the finest of margins by VAR - they got their fifth through sub Martial. Latching onto Fernandes' brilliant, lofted ball into the box, the Frenchman chested, wrestled off Bednarek and lashed into the roof of the net to end his goal drought.
It was 6-0 just two minutes later as McTominay drilled into the bottom corner from range as the ball squirmed to him, and United kept their sheets clean as Adams blazed over a fine chance at the other end.
Martial then dinked inches wide, but United still weren't done. Bednarek saw red as he brushed past Martial in the box - rules state if last-man defenders bring down attackers without attempting to play the ball, they will be sent off - and Fernandes despatched from 12 yards for 7-0.
Manchester United dropped Paul Pogba to the bench, with Mason Greenwood coming into the starting XI in the only change from the 0-0 draw at Arsenal on Saturday.
Saints made four changes from the 1-0 defeat by Aston Villa on Saturday; Theo Walcott, Ibrahim Diallo and Oriol Romeu were all injured, while Nathan Redmond dropped to the bench, meaning Kayne Ramsay, Alexandre Jankewitz, Moussa Djenepo and Che Adams came in.
It was young right-back Ramsay's and midfielder Jankewitz's first Premier League starts.
More was to come as Martial got his second, chesting down Wan-Bissaka's cross and firing past the hapless McCarthy, and fellow sub James put the cherry on the cake with a close-range finish from Fernandes' cushioned header.
Hasenhuttl looked distraught at the final whistle, his opposite number Solskjaer almost embarrassed at the scoreline, and though VAR threatened to take the headlines with several debatable calls, United's ruthless edge in front of goal was the story. Will this thrust them back into the title race?
What the managers said...
Man Utd boss Ole Gunnar Solskjaer: "What I liked about the performance was the hunger and attitude to do the right things, get better and better, practice the good habits, and that's the only way we can improve and get better.
"You can see loads of things we were working on; but we don't want to be predictable, we want to be a bit unpredictable, and that has to come from the players. The freedom, creativity and imagination was there. The performance was positive and something we can look at - of course you have to look at them having 10 men, but it's never easy playing against 10 men either."
Speaking to BT Sport: "We have been waiting for them [the front players] to show the magic, and tonight was the night for them to go and enjoy, we haven't had too many of them. They enjoyed it and there were some good performances. Yes, they have [recovered their mojo]. There were a lot of good performances and a result like this, scoring goals, is always good for the team."
Saints boss Ralph Hasenhuttl: "We lost in a horrible way, and 90 minutes can be long in the Premier League. We couldn't help them from outside. In the end, it's a little bit of a different situation [to the 9-0 defeat by Leicester] because we are in a position in the table where we haven't been for a long time.
"You don't need this result to know what we need to do better. The team is a different one now, that's the reason we've played a good season so far. Let's see how the season ends, it will end better than the last I think.
"It hurts, but I can't change it anymore. It happened. The only way for us to go on is to show that we are a better team than we showed today."
On Jankewitz's red: "It's a young player who has to learn a lot, but today it was a horrible start for him."
United's rout in stats
- Manchester United had seven different scorers, only the second time a team has had seven different scorers in a Premier League match, after Chelsea vs Aston Villa in December 2012.
- Manchester United have scored six or more goals in a Premier League match for a second time this season (also 6-2 vs Leeds); it's the first time they've hit 6+ goals twice in a season since 2000/01 (vs Bradford and Arsenal).
- After winning just one of their first six Premier League home games this season and scoring just three goals, Manchester United have won four of their last five (L1), netting a total of 19 across those games.
- Manchester United scored four goals in the first half of a Premier League game for the second time this season, also doing so against Leeds. It's the first time they've scored 4+ goals in the first half of two games in a season since 1997/98 under Sir Alex Ferguson.
Man Utd now host Everton on Saturday in the Premier League, live on Sky Sports Premier League at 8pm, before hosting West Ham in the FA Cup fifth round on Tuesday at 7.30pm.
Southampton go to Newcastle on Saturday at 3pm in the Premier League, before a trip to Wolves in the FA Cup fifth round on Tuesday at 5.30pm.