Arsenal ground out a 1-0 win over Brighton to capitalise on Manchester City's slip-up against Nottingham Forest and move seven points clear at the top of the Premier League.
As their title rivals were held to a 2-2 draw at the Etihad Stadium, Bukayo Saka's deflected, eighth-minute strike proved decisive for the Gunners in a tough encounter on the south coast.
Saka's strike, which wrong-footed Bart Verbruggen after taking a touch off Carlos Baleba, came from one of only two shots on target by Arsenal but Mikel Arteta's side excelled defensively.
Brighton dominated most of the game, registering 60 per cent of the possession, but Arsenal, led by defenders Gabriel and Piero Hincapie, and without the injured William Saliba, could not be breached.
Brighton's best chance came after only two minutes, when David Raya sent a pass straight to Baleba, whose attempted chip had to be cleared off the line by Gabriel.
They pinned Arsenal in their own half for long periods, but only mustered a further two shots on target, with Raya saving well from Georginio Rutter as the home fans became increasingly frustrated by perceived time-wasting from the visitors.
Arsenal had a chance to put the game beyond Brighton when substitute Kai Havertz had a diagonal effort saved by Verbruggen, but their slender lead meant they had to survive a nervy finale.
The final whistle, and news of Manchester City's draw with Forest, prompted wild celebrations from the travelling fans as Arsenal opened up a seven-point gap, albeit having played a game more.
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