Kai Havertz headed in the winner for Arsenal with four minutes left, as they saw off Brentford 2-1 on Saturday.
The game was level after Yoanne Wissa pounced on Aaron Ramsdale’s error to cancel out Declan Rice’s opener.
Ramsdale’s blunder looked as if it might cost Arsenal ahead of Sunday’s huge title showdown between Liverpool and Man City at Anfield.
But Havertz delivered with a header late on, just as he did in the reverse fixture in November.
The result takes Arsenal a point clear of Liverpool and two of City with their eighth consecutive league win.
The hard-fought victory puts Arsenal in provisional top spot on 64 points, one point ahead of Liverpool and two in front of Manchester City — who play each other at Anfield on Sunday.