Emile Smith Rowe scored in a third successive Premier League game as Arsenal claimed victory over Watford in manager Mikel Arteta's 100th match in charge.
The in-form Smith Rowe registered the 100th league goal of Arteta's tenure with a low drive from outside the box after 56 minutes.
Gunners captain Pierre-Emerick Aubameyang had a first-half penalty saved by Ben Foster following a poor challenge by Danny Rose on Alexandre Lacazette - and the Hornets goalkeeper produced another fine stop to keep out Gabriel's header shortly before half-time.
Watford were fired an early warning when Bukayo Saka had an eighth-minute finish ruled out for offside at Emirates Stadium.