A late own goal from Watford's Craig Cathcart and a Mesut Ozil strike two minutes later gave Arsenal a 2-0 win at the Emirates on Saturday that sent them above the Hornets in the Premier League table.
Watford, who had beaten Arsenal twice in their previous three Premier League meetings, created numerous chances throughout the match but were unable to find the back of the net.
Instead, in the 81st minute, defender Cathcart inadvertently put the visitors behind when he flicked the ball into his own net as he tried to prevent Arsenal striker Alexandre Lacazette from collecting and shooting right in front of the goalpost.
Two minutes later, the Frenchman sent a low pass across the face of goal to the far post, where German midfielder Ozil sidefooted in an easy goal to double the lead to 2-0, a score that flattered the home side after an even, open and attacking match.
Arsenal manager Unai Emery told reporters that his players had been cautious in the first half as Watford pressed forward but that they picked up the pace after the break.
"We improved things on the pitch with the positioning, and then our moments are arriving to score," he said. "They are a very organised team and very competitive, finding their best performance."
The result meant Watford drop to sixth in the Premier League table, swapping places with the Gunners.
"I'm very disappointed for my players because I think they deserved more, and they created certain chances to score," Watford manager Javi Gracia said. "But today, one more time, I'm very proud of my players."
Both teams charged into action in the first half, creating a string of chances at each end.
In the fifth minute, Lacazette ran in on goal and was unlucky not to win a penalty when he was brought down in the area by Watford defender Christian Kabasele.
Watford's Will Hughes edged the ball just wide of Petr Cech's goal just moments later.
Lacazette had the clearest chance of the half when he stole the ball off Cathcart not far from the centre circle and raced alone towards goal, only to send his chipped shot a few yards wide of goal.
Cech was forced off just before the half-time whistle when he pulled a hamstring while taking a goal kick.
He was replaced by German summer signing Bernd Leno, who made numerous saves in the second half, including stopping a point-blank thunderbolt shot from Watford substitute Isaac Success in the 75th minute, to help the Gunners to their second clean sheet in a row in the league.