Declan Rice scored his first West Ham goal as Arsenal's top four hopes were dented following defeat at the London Stadium
The result means Manchester United will move level with Unai Emery's men with a victory at Tottenham on Sunday and could even overtake Arsenal should they win by three goals or more.
Arsenal old boy Samir Nasri made his first Premier League start for West Ham against his former club and almost produced an assist in the first half when he showed great composure to hold the ball up and lay the it off to Felipe Anderson on the edge of the box.