Arsenal slipped to back-to-back Premier League defeats as Ollie Watkins' early strike gave Aston Villa a Premier League double over the Gunners.
Watkins had scored twice as Villa won at the Emirates in November and the former Brentford man was on target again here, his second-minute effort proving the only goal of the game.
Mikel Arteta made two changes to his side, both of them enforced following the sendings off of David Luiz and Bernd Leno at Wolves in midweek, as Gabriel came into the heart of defence while Brighton loanee Mat Ryan made his debut in goal.
The Australian's first act was to pick the ball out of his own net after a mix-up between Gabriel and Cedric Soares allowed Bertrand Traore to feed Watkins and the striker's low finish took a small deflection and found the far corner.
Arsenal's best opportunity to score an equaliser came from a Granit Xhaka free kick which looked destined for the top corner until their own former goalkeeper Emiliano Martinez at full stretch pushed it around the post with a fingertip save.
While Villa leapfrogged struggling Tottenham Hotspur, the result left Arsenal in 10th with 31 points, two points behind their north London rivals having played two games more.
Additional reporting by PA.
