Alex Iwobi was on for 90 minutes as Arsenal survived a second-half rally from Brentford with 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.