Arsenal boss Mikel Arteta praised "exceptional" Aaron Ramsdale on his return to the team as the Gunners won at Brentford in the Carabao Cup third round.
Reiss Nelson scored the decisive goal in the eighth minute after a mistake in defence by the hosts.
But the display of goalkeeper Ramsdale, benched in favour of David Raya in Arsenal's last three games, proved pivotal in ensuring Arteta's side booked a fourth-round meeting at West Ham.
He caught the eye when he made a crucial second-half save from Yoane Wissa as Brentford put the visitors under heavy pressure in the second half.