Arsenal underlined their title credentials by producing a second-half fightback to beat West Ham and move seven points clear at the top as the Premier League returned after the World Cup.
West Ham took the lead against the run of play when Jarrod Bowen was judged to have been clipped in the box by William Saliba, allowing Said Benrahma to smash a confident penalty down the middle.
There was a mood of frustration among the home fans until Bukayo Saka converted from close range after collecting Martin Odegaard's mis-hit shot.
The equaliser gave increased impetus to the Gunners and another home goal looked increasingly likely.