Arsenal s Spanish manager Mikel Arteta gestures on the touchline during the English Premier League football match between Arsenal and Watford at the Emirates Stadium in London on November 7, 2021. AFP
Emile Smith Rowe broke the deadlock in the second half after an inspired performance from Watford goalkeeper Ben Foster had frustrated the hosts, with Juraj Kucka dismissed late on at the Emirates Stadium.
The three points mean Arsenal, unbeaten in 10 games in all competitions, leapfrog Brighton and Manchester United.
Watford are just two points above the relegation zone after three defeats in four league matches under new boss Claudio Ranieri.
The Gunners last season failed to qualify for Europe for the first time in 26 years but they are now unbeaten in 10 games in all competitions.
The home side thought they had taken a seventh-minute lead when Bukayo Saka tucked away a loose ball in the area after Foster parried Alexandre Lacazette's chip.
But the goal was disallowed for offside following a VAR check.
Arsenal were awarded a penalty when former Tottenham defender Danny Rose rashly thrust his arm into Lacazette's head in the 34th minute.
But 38-year-old Foster superbly saved Pierre-Emerick Aubameyang's unconvincing spot-kick.
Kucka produced Watford's brightest first-half moment when he dispossessed Albert Sambi Lokonga and saw his shot deflected just wide by Ben White.
Foster continued to keep Arsenal at bay, making another sharp save with his foot to deny Gabriel's firm header from a corner shortly before half-time.
But Smith Rowe broke the deadlock in the 56th minute, scoring his third goal in as many Premier League games when his strike from the edge of the area ricocheted off Craig Cathcart and into the net.
He joined club greats Nicolas Anelka, Jose Antonio Reyes and Cesc Fabregas in scoring in three straight Premier League games for Arsenal aged 21 or younger.
Aubameyang's forgettable day continued when he poked home Martin Odegaard's goal-bound shot in an offside position.
Aaron Ramsdale had a nervy moment late on when he rushed from his goal and failed to clear the ball but Josh King hit the side-netting from a tight angle.
Kucka was sent off in the 89th minute after receiving a second yellow card for a late challenge on Nuno Tavares, while Foster denied Lokonga in added time.
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