Enzo Fernandez was not deemed to have played the ball in the build-up to Erling Haaland's winning goal against Manchester United.
Haaland's brilliant finish to give 10-man Manchester City a memorable victory at Old Trafford was initially ruled out for offside, before that decision was overturned following a lengthy VAR check.
Replays revealed Haaland had been played onside, by the slenderest of margins, by Patrick Dorgu's outstretched foot, as shown by the semi-automated offside technology.
However, there remained some confusion as Fernandez had moved towards the ball as it travelled across the Man United goal, perhaps stopping Lisandro Martinez from intercepting.
And Man United legend Gary Neville, commentating for Sky Sports, questioned the reversal of the initial offside call.
"The officials will be nervous about this goal," he said.
"When they look back on this, they will recognise they got this wrong.
"The question is does Fernandez, who is offside, stop Martinez getting the ball? He does."
The Premier League later explained the decision via Premier League Match Centre on X, posting: "VAR checked the refereeâÂÂs call of no goal for offside â and determined that Haaland was in an onside position and recommended that the goal was awarded.
"The VAR also deemed that while in an offside position, Fernandez didnâÂÂt play the ball."
Man City had been reduced to ten men midway through the first half after Phil Foden was controversially sent off for kicking out at Bruno Fernandes.
But United were unable to make their numerical advantage count as City maintained their 100 per cent start to the season against the odds.
They became just the second away side to win at Old Trafford in the Premier League after having a player sent off.
Everton made history by becoming the first to achieve that feat with a 1-0 triumph last November.
Bryan Mbeumo had a fantastic opportunity to salvage a point for United deep into injury time but was thwarted by Gianluigi Donnarumma.
The result sends Enzo Maresca's side level on points at the top of the Premier League with Arsenal, who made it four wins out of four at the start of their title defence with a hard-fought 2-0 victory at Sunderland on Saturday.
It's the first time City have won at Old Trafford for almost three years, since a 3-0 success in October 2023.
They'll look to make it five Premier League wins from five when they entertain Sunderland next Sunday in their final fixture before the international break.
United, meanwhile, will aim to bounce back away to Fulham.