Arsenal survived a second-half rally from Brentford as a Danny Welbeck double proved enough to seal a place in the fourth round of the Carabao Cup.
The Gunners, beaten finalists in this competition last season, were pushed all the way by a much-changed Brentford side but showed enough to advance with a 3-1 win.
At a sparsely populated Emirates Stadium - not helped by a London Underground strike - Welbeck scored twice in the first half to ensure safe progression.
The visitors were the better side after the interval and gave themselves a fighting chance of an upset courtesy of a fine Alan Judge free-kick, only for substitute Alexandre Lacazette to secure the win with a stoppage-time effort.
Unai Emery again made plenty of changes, Emile Smith Rowe making his full debut as one of nine players to come into the team as the likes of Mohamed Elneny, Bernd Leno and Alex Iwobi were given another chance to stake their claims for a place in the Premier League side.
After suffering just their second league defeat of the season at the weekend, Dean Smith made seven alterations to his Brentford side as only Ollie Watkins, Romaine Sawyers, Julian Jeanvier and Yoann Barbet kept their places.
Arsenal did not have to wait long to break the deadlock, Welbeck guiding a header past Luke Daniels with just four minutes on the clock.
It could have been two just moments later as a raking ball forward from Elneny was collected by Smith Rowe, who burst through on goal only to see his shot blocked by the recovering Jeanvier.
Arsenal could not build on their lead and their Sky Bet Championship visitors began to grow in confidence, Watkins earning a corner after two mistakes from Shkodran Mustafi allowed him to run at the defence.
But as their belief started to grow, so Brentford were soon hit by the sucker punch of a second Welbeck goal.
Henrikh Mkhitaryan lead an attack which saw Iwobi feed Nacho Monreal, whose loose cross was turned home by the England international.
Iwobi fired over the bar at the start of the second half as Emery's side looked to kill off the contest, with the Bees threatening occasionally as Sergi Canos shot just wide.
Brentford were finely rewarded for their exerted efforts as Judge whipped in a superb free-kick on the hour mark to half the arrears.
Canos came close again moments later, rousing the travelling support as they searched what had seemed an improbable equaliser.
Judge then forced a save out of Leno as Emery introduced Lacazette for Smith Rowe in an attempt to sew up the tie.
At the other end, Daniels did well to keep out a close-range Monreal effort as Brentford's push for an equaliser started to wilt.
Lacazette exchanged passes with fellow substitute Aaron Ramsey before firing wide before Yoann Barbet was left calling for a last-minute penalty for Brentford after a coming together with Lucas Torreira - but referee Mike Dean was unmoved.
Arsenal wrapped the tie up in stoppage time as Lacazette finished with aplomb, with Arsenal extending their winning run in all competitions to six games in the process.