Gabriel Magalhaes' second-half header earned Arsenal a crucial 1-0 win at Tottenham Hotspur in a feisty north London derby on Sunday to keep pace with early Premier League leaders Manchester City.
Spurs started sharper and David Raya was forced into early saves, turning Dejan Kulusevski's first-time effort behind before he clawed away a dangerous cross from the Sweden winger.
Record signing Dominic Solanke, making his home debut, squandered a good opening in the 14th minute after Arsenal lost possession deep in their own half, taking too long on the ball and allowing William Saliba to recover.
Arsenal fought their way into the contest, with Guglielmo Vicario tested by a Kai Havertz header before Gabriel Martinelli scuffed his shot with Bukayo Saka waiting centrally.
Jurrien Timber was perhaps fortunate to avoid a straight red card in the first half for a reckless challenge on Pedro Porro as he tried to retain possession.
His studs landed on Porro's ankle but referee Jarred Gillett deemed the incident was not serious foul play and VAR declined to intervene, much to the Spurs fans' anger.
The second half started in similar fashion to the first, with the hosts on top as Micky van de Ven tested Raya with a glancing header, before Arsenal again got a foothold in the game.
The game had been breathless but low on quality in front of goal until Arsenal punished Spurs from a corner, having done so twice in last season's 3-2 away win in April.
Gabriel escaped far too easily from Cristian Romero, who pleaded for a foul in vain, and powered a header past Vicario from close range in the 64th minute.
Arsenal withstood some late pressure from Spurs, who created few real chances and were left shooting from range as the Gunners seemed happy with a one-goal lead.
The win, their third in a row away to their bitter rivals, puts Arsenal on 10 points from four games, two behind champions Manchester City ahead of their trip to the Etihad next Sunday.
Spurs, once again left to rue missed chances, have four points from four games.
