Cristiano Ronaldo saved Manchester United in stoppage time as Villarreal were floored at Old Trafford.
The La Liga outfit - who beat United on penalties in last season's Europa League final - were the better side in the first half, and saw their endeavour rewarded when Arnaut Danjuma crossed for Paco Alcacer to score at the start of the second period.
United full-back Alex Telles soon levelled with a brilliant volley from a Bruno Fernandes free-kick, but Ole Gunnar Solskjaer's side looked as though they would be unable to force the winner as substitute Edinson Cavani headed wide.
Ronaldo then found the net in the dying seconds to spark delirious scenes.
Here are the game's main talking points.
1. United indebted to David de Gea
David de Gea was at his best in the first half ( Image:
AFP via Getty Images)
The sight of the yellow Villarreal shirts might have triggered something in David de Gea, just four months on from his penalty shootout misery in the Europa League final.
Back then it wasn't much that he missed the decisive one in that seemingly endless parade of attempts from 12 yards, more that he didn't get anywhere near barely any of the kicks that the side from his homeland took.
That was the end of what had been a pretty disappointing season for the goalkeeper, now rather openly challenged by Dean Henderson for the No.1 spot, but he has started the new campaign positively.
With Henderson unfortunately struck down by Covid, De Gea has taken his chance to re-establish himself as the club's No.1.
There have been strong Premier League performances, the highlight being that penalty save from Mark Noble, and here he was needed to stand up tall in the early exchanges as he saved impressively from Danjuma and Alcacer.
2. Arnaut Danjuma dazzles
Danjuma was excellent down the Villarreal left ( Image:
Getty Images)
The Dutchman has impressed ever he swapped Bournemouth for Villarreal in the summer, and there were suggestions that Liverpool scouts were in attendance at Old Trafford to keep track of the 24-year-old's rapid progress.
He's pretty quick on the pitch too, and it was he who the Spanish side were looking towards in the opening exchanges as they pinned United back at times.
He then took more of a hold on the game, and was heavily involved in Alcacer's strike which put the visitors in front.
Drifting in from the left on his right foot, Danjuma has drawn comparisons with Liverpool's Sadio Mane, and he was tentatively linked to the Reds even before he left the Cherries.
He's clearly a raw talent, but he looks to be one that a club like Liverpool could mould.
3. Diogo Dalot does little to dissuade doubters
Diogo Dalot endured a difficult first half against Danjuma ( Image:
Getty Images)
Every club has squad players, and every club has players who aren't quite as good as the ones who are usually in the team ahead of them, and sometimes we are reminded why that is the natural order of things.
There were many who thought that Diogo Dalot, a Jose Mourinho signing, would never return to United when he left for AC Milan last summer, but return he did.
United's failure to sign Kieran Trippier in the summer gave the Portuguese another life at United, but playing here instead of Aaron Wan-Bissaka he didn't really take it.
Danjuma had him on toast in the first half, and his positioning was nowhere near as good as the man he was replacing.
4. Alex Telles more than plays his part
Telles celebrates his terrific strike which brought United level ( Image:
Getty Images)
Of course everything we say about Dalot's status in the squad above also applies to Alex Telles, who was in here in place of the injured Luke Shaw.
The Brazilian has been a useful squad member for United since his arrival from Porto, but no-one would have him in their first-choice XI to replace the England man, partly due to the gap in quality but also due to Shaw's almost continuous improvement ever since he escaped the clutches of Jose Mourinho.
All of which means there was something very sweet about Telles' brilliant goal that brought United level.
It was a superb hit, and if it proves to be the highlight of his United career then it was a pretty good one.
5. Jadon Sancho fails to take another chance
Jadon Sancho was making his eighth appearance for United ( Image:
AFP via Getty Images)
And so another game passes Jadon Sancho by.
The summer arrival from Borussia Dortmund is clearly a talent and, lest we forget, is just 21 years old. His time will come at United, even if they do currently seem obsessed with attackers in their mid-30s.
But he could just do with making a dent in the public consciousness sooner or later, as eight games into his career with his new club it really is quite hard to think of anything he's actually done.
His early withdrawal was an expected one, even as United chased a winner.