Jarrod Bowen scored a stoppage-time winner for West Ham to pile more pressure on under-fire Manchester United manager Erik ten Hag on Sunday.
The 2-1 defeat at the London Stadium was a fourth loss of the season for the Manchester giants and saw them slip to 14th in the Premier League table – one place below the Hammers, who also have 11 points from nine games.
The result takes some of the heat off Hammers boss Julen Lopetegui.
The Spaniard made three substitutions at half-time and one of those, Crysencio Summerville opened the scoring for the home side.
The £25 million summer signing from Leeds United slid in to put them ahead after 74 minutes before Casemiro levelled for United with a point-blank header after 81 minutes.
But there was late drama as VAR intervened to rule that Matthijs de Ligt had fouled Danny Ings in the box.
Bowen stepped up to smash the penalty home and secure the three points.
After the match, Ten Hag told BBC's Match of the Day: "Three times this season we feel injustice. Unfair and unjust the way we conceded the penalty.
"Before the season there was the instruction about VAR only interfering in clear and obvious mistakes. That is definitely not a clear and obvious mistake from the on field referee."
Lopetegui said: "Happy for the three points. We are happy for the fans and players, they deserve this victory after suffering a lot in the first half.
"Second half we changed different things and the first half was for them but the second was for us. We were able to compete better and win the match."
In South London, Crystal Palace clinched their fist win of the season thanks to Jean-Philippe Mateta's first-half strike against Tottenham Hotspur.
After being called back to the starting line-up, the Frenchman scored after being teed up by Eberechi Eze's deft flick to notch his third goal of the season.
Eze had a second ruled out for offside in the second half, but Tottenham, without injured captain Son Heung-min, were toothless in attack.
Spurs goalkeeper Guglielmo Vicario said to Sky Sports: "They fight and I think we lacked that today. We are disappointed because we have to fight. We play good football but maybe sometimes we lack the desire to fight. They show a real desire to fight for something."
On Son's absence, he said: "He is the captain but we have a big squad and we have to deal with that. We have to be able to win games without Son. We lacked in something, not in football, but attitude and fight."
