Eberechi Eze scored against his former club as Arsenal beat Crystal Palace to extend their lead at the top of the Premier League table to four points.
Eze joined the Gunners in a deal worth £67m in the summer and his winner came from another trademark Arsenal set-piece.
Declan Rice curled a free-kick into the area which was knocked down by centre-back Gabriel, then Eze acrobatically fired the ball into the corner of the net.
Crystal Palace, who lost to AEK Larnaca in midweek, did threaten on occasion with Jean-Philippe Mateta battling against the solid Arsenal defence – but they did not trouble David Raya in goal.
Arsenal nearly doubled their lead in the second half when Gabriel hit the crossbar with a header and Bukayo Saka went close with a curled effort from the edge of the penalty area.
The win means Arsenal are now unbeaten in 10 matches in all competitions.