Marcus Rashford hit a quickfire hat-trick off the bench as Manchester United swept aside RB Leipzig with a stunning 5-0 victory in the Champions League.
Mason Greenwood (21) broke the deadlock in what was an even first half before Rashford, who came on in the 63rd minute, took over.
The England striker, whose name is already in the headlines off the pitch for his continued fight against the Government over free school meals for school children, scored twice (74, 78) in four minutes before Anthony Martial's first goal of the season (87) added a fourth from the penalty spot after the Frenchman was brought down by Marcel Sabitzer.
Rashford (90+2) then rounded off United's perfect evening, completing his first senior hat-trick as Ole Gunnar Solskjaer's side made it back-to-back wins in Europe to go top of Group H.
The 22-year-old wrote on Twitter after the game: "Can't stop smiling, I've waited a long time for that. Just wish the fans were in to experience it with me."
How Rashford and United stunned the Bundesliga leaders
After what was a fairly even opening at Old Trafford, United took the lead when Greenwood beat the offside trap to pick out the far corner with a clinical finish after being released by Paul Pogba's through-ball.
Despite finding themselves behind, RB Leipzig responded well to United's goal with Julian Nagelsmann's side dominating possession and looking a threat on the counter-attack.
David de Gea's reflexes had to be sharp to keep out Christopher Nkunku's powerful drive, while Dayot Upamecano wanted a penalty after being shoved by Pogba, but his claims were ignored just before the half-time whistle.
Man Utd: De Gea (7), Wan-Bissaka (8), Lindelof (7), Maguire (7), Shaw (7), Fred (7), Matic (7), Pogba (7), Van de Beek (7), Greenwood (8), Martial (7).
Subs: Rashford (9), McTominay (6), Fernandes (7), Tuanzebe (n/a), Cavani (n/a).
Away Team: Gulacsi (5), Angelino (5), Upamecano (5), Konate (6), Poulsen (5), Forsberg (6), Nkunku (6), Halstenberg (6), Olmo (6), Henrichs (5), Kampl (5).
Subs: Sabitzer (5), Sorloth (5), Kluivert (5).
Man of the match: Marcus Rashford
With only a slender lead, Solskjaer turned to his bench and it proved to be a superb decision as Rashford took full control of the game.
The England forward latched onto Bruno Fernandes' through-ball before finishing comprehensively, but the offside flag went up quickly. However, VAR gave the goal the green light with Rashford starting his run in his own half.
It gave United some breathing space and Rashford made the game safe four minutes later, bursting past Upamecano before finding the bottom corner again.
United started to enjoy themselves as they cut through Leipzig for fun and Martial added a confidence-boosting goal from the spot after being brought down in the penalty area by Sabitzer's last-ditch tackle.
Man-of-the-moment Rashford then added United's fifth to complete a stunning hat-trick, which will keep his name in the headlines a little bit longer.
Donny van de Beek and Paul Pogba started for Manchester United. The pair have been conspicuous by their absence from recent starting line-ups but were brought in among five changes made by manager Ole Gunnar Solskjaer.
Alex Telles was absent from the squad for the Group H clash at Old Trafford after testing positive for coronavirus, with Manchester City loanee Angelino among the starters for Leipzig.
Also in Group H...
PSG got off the mark in the Champions League in Turkey with a 2-0 win away to Istanbul Buyuksehir thanks to Moise Kean's second-half double, although Neymar went off injured.
Solskjaer: We have a strong squad
Man Utd boss Ole Gunnar Solskjaer was full of praise for his squad after their emphatic win over RB Leipzig.
"It was a case of using the squad. We had to rest a few players and the ones who came in did brilliant.
"We had to work hard for this, they really made us work hard off the ball and on the ball as well because they counter pressed. The intensity of their play was incredible
"After 2-0 of course they open up, go for goals and the spaces opened up for our fresh legs out there.
"It's very good to know for the players that we have a strong squad to pick from. We are very happy with the start. We have played against two very good teams, two difficult games, and we have performed fantastic. We showed our own quality and if we focus on the next job and the next job and the next job who knows how far they are going to go. We go to Istanbul next week wanting three points there as well."
What the managers said...
More from Ole Gunnar Solskjaer: "Marcus Rashford came on and did well but the groundwork was there from the team, that's what you want from the subs. What a shift they put in. Leipzig are a high press, the intensity, so we had to dig deep.
"We had to rest a few because the season is relentless, so we used the squad. This group is coming together. The more quality and spirit you have, the more you get the performance.
"We made some changes today because of Sunday as you have to be ready for that. In the league you have a game less than other teams as well. We need to pick up points."
RB Leipzig boss Julian Nagelsmann: "It was a bit crazy because after they scored the first goal, we did well. The final 20 minutes were very bad."
On whether the first goal was offside: "We can defend it better, that's the more important topic for me as the manager. You can follow the deep run and then normally it's no trouble."
Man of the match - Marcus Rashford
There will be only one name on the front and back pages of Thursday's newspapers!
You just cannot keep Marcus Rashford out of the headlines.
Off the pitch, an online petition launched by the 22-year-old to expand access to free school meals during school holidays has surpassed one million signatures as he continues to fight against the Government's policy,
And on the pitch on Wednesday evening, he produced a scintillating game to score a brilliant hat-trick from the bench.
He is only the second Manchester United player to score a hat-trick as a substitute after his manager Solskjaer did so versus Nottingham Forest in February 1999 in the Premier League.
He is also just the fifth player in UEFA Champions League history to score a hat-trick as a substitute, though his 27-minute cameo is the fewest number of minutes played while netting a treble in the competition.
Opta stats - United's emphatic evening
Manchester United's victory was Ole Gunnar Solskjaer's 50th match as a manager in UEFA competition (incl. qualifiers), with the Norwegian overseeing 11 wins in 18 such matches for United (61%).
United have kicked off a UEFA Champions League campaign with back-to-back wins for only the second time since Sir Alex Ferguson left the club in 2013, also doing so under Jose Mourinho in 2017/18.
RB Leipzig conceded more goals this evening (5) as they had across their previous seven games combined in all competitions this season (3).
Leipzig's 5-0 defeat is their heaviest loss in their short European history, while the scoreline represents Manchester United's biggest victory in the UEFA Champions League since November 2013 v Bayer Leverkusen (5-0).
Manchester United host Arsenal on Super Sunday, live on Sky Sports Premier League and Sky Sports Main Event; Kick-off at 4.30pm.
RB Leipzig are back in action on Saturday, and face a trip to mid-table Borussia Monchengladbach; Kick-off at 5.30pm.
Source: Sky Sports