Erling Haaland scored the decisive goal as 10-man Manchester City claimed a controversial 1-0 victory over Manchester United at Old Trafford.
City played more than 70 minutes with a numerical disadvantage after Phil Foden was shown a straight red card for kicking out at Bruno Fernandes.
The dismissal allowed United to take control, but the hosts failed to capitalise and struck the woodwork on either side of half-time.
Despite being under pressure, City broke the deadlock in the 60th minute when Haaland converted Josko Gvardiol’s low, deflected cross at the back post.
The striker was initially flagged for offside, but a lengthy video assistant referee review overturned the decision after replays showed Patrick Dorgu’s toe had played him onside.
The decision remained controversial because Enzo Fernandez, who was standing in an offside position, attempted to connect with the cross before it reached Haaland.
Officials ruled that he had not interfered with play, despite United goalkeeper Senne Lammens appearing to react to his attempted diving header.
Victory maintained City’s perfect start under new manager Enzo Maresca and moved them level on points with Arsenal at the top of the Premier League table.
United, meanwhile, dropped points for the third time in four matches and remained 13th.
City faced an uphill battle when Foden became only the second player from the club to be sent off in a Premier League Manchester derby, following Bernardo Corradi in December 2006.
The midfielder caught Fernandes in the chest with his studs while sitting on the ground.
Moments earlier, the United captain appeared to kick Foden in the back but escaped without a booking.
City responded impressively to the dismissal, defending with discipline and limiting United’s opportunities before striking on the counterattack.
Their winning goal depended on two tight decisions.
Haaland was marginally kept onside by Dorgu, while Fernandez was judged not to have affected play despite attempting to reach the cross.
Manchester United were left frustrated after failing to make their extra player count, in a performance reminiscent of their 1-0 defeat by 10-man Everton last season.
Marcus Rashford came close to opening the scoring shortly before half-time when his dipping free-kick struck the post.
Kobbie Mainoo then hit the woodwork five minutes after the restart.
His curling long-range effort rebounded off the post and struck City goalkeeper Gianluigi Donnarumma before falling safely into the Italian’s hands.
United created little after falling behind, with their best late opportunity coming when Fernandes found Bryan Mbeumo inside the penalty area.
His powerful effort was pushed behind by Donnarumma.
The Red Devils ended last season strongly, but their disappointing start to the new campaign has brought only one league victory, while they are yet to keep a clean sheet.
