Arsenal shot to first place on the Premier League table on Saturday evening after Kai Havertz scored an 89th-minute winner against Brentford in the London Derby.
The German forward headed home in the 89th minute to secure a narrow victory for the Gunners, who had struggled against their stubborn city rivals.
Arsenal started brightly and could have taken the lead in the early stages, but Bukayo Saka and Gabriel Jesus both wasted excellent opportunities.