Arsenal ended a run of three successive Premier League defeats with a morale-boosting 3-0 victory over Watford at the Emirates Stadium on Sunday.
Goals from Shkodran Mustafi and Pierre-Emerick Aubameyang early in each half saw the Gunners build on their Europa League victory at AC Milan on Thursday.
Troy Deeney missed a second-half penalty to get Watford back in the game as Petr Cech became the first goalkeeper to reach 200 Premier League clean sheets.
Aubameyang was one of six players recalled as Arsene Wenger rotated ahead of next week’s return leg with the Italians, and had a golden opportunity to score inside three minutes.
The Gabonese striker was released by Mesut Ozil’s slide-rule pass but saw his powerful shot blocked by Oscar Karnezis.
Arsenal’s opener came five minutes later when Ozil swung in a free kick which Mustafi directed back across Karnezis and into the top corner, after being allowed to run in between two Watford defenders.
The visitors had a couple of opportunities to equalise in the first half as Cech saved from Abdoulaye Doucoure, and Roberto Pereyra blazed over the crossbar after the Gunners goalkeeper had parried a Richarlison free kick.
Cech also dived low to his left to keep out a header from the Brazilian in stoppage time as Watford finished the first half the stronger, and they continued this momentum into the second period only to be hit by a sucker-punch.