Arsenal missed an opportunity to move up to fourth position in the Premier League table ahead of Chelsea after losing by a lone goal to Sheffield United.
Sheffield United’s victory moved them into the top half of the Premier League.
Lys Mousset marked his first start for the Blades with the decisive goal in the first half, turning in Jack O’Connell’s knockdown from close range.
Arsenal’s £72m signing Nicolas Pepe had earlier skewed a golden chance wide from six yards.
Granit Xhaka forced Dean Henderson into an excellent save but the Blades closed the game out superbly for a famous win.
The victory was Sheffield United’s biggest result since their return to the Premier League as they moved up to ninth, four points clear of the relegation zone.