As Erik ten Hag's team ended Arsenal's perfect start to the season at Old Trafford, the £82 million new boy from Manchester United, Antony, scored on his debut and Marcus Rashford added two more goals.
In the tense match, the Brazilian scored the game's first goal 10 minutes before halftime by stroking a shot into the far corner.
After Bukayo Saka had equalized on the hour, Rashford took credit for the assist and later benefited from two superb United counterattacks.
Bruno Fernandes was at the heart of both, splitting the Arsenal defence for Rashford's first, then sending Christian Eriksen clear as the Dane provided the striker with a tap-in.
It was Rashford's first Premier League double since December 2020, helping lift them to fifth in the table.
Arsenal remain top. However, after their excellent start to the season, manager Mikel Arteta will be concerned at how easily his side were opened up, although the Gunners did have a first-half Gabriel Martinelli goal ruled out by VAR.
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