Arsenal's 12-match home winning streak in the Premier League ended as Jesse Lingard scored twice in a thrilling 3-1 victory for second-placed Manchester United.
Skipper Antonio Valencia and Lingard punished woeful Arsenal defending to put United two ahead inside 11 minutes at the Emirates Stadium and Lingard struck again in the 63rd minute after Alexandre Lacazette's goal revived home hopes.
United who had to play the final 15 minutes with 10 men after record signing Paul Pogba was shown a straight red card for a reckless 'studs up' foul on Arsenal right back Hector Bellerin.
United's first away victory over a "top-six"' rival since Jose Mourinho took charge meant they cut Manchester City's lead to five points, although Pep Guardiola's side host struggling West Ham United on Sunday.
Earlier, Huddersfield were unable to prevent new coach Sam Allardyce starting his Everton reign with a 2-0 victory.