Here are how players from both teams rated:
Ben Foster -6
The 35-year-old made his first Hornets appearance for 11 years after joining from West Brom in the summer. Little to do but nicely claimed a couple of crosses in the closing stages.
Daryl Janmaat -7
Couple of proping runs down the right and looked dangerous with the ball at his feet.
Craig Cathcart -7
Solid at the back up against Glenn Murray. Comfortable afternoon.
Christian Kabasele -7
Partnered Cathcart well in the centre of defence to limit Albion's chances. Headed a great chance over early in the second half.
Jose Holebas -8
Free kick deflected behind for corner. Had to be on his game against the tricky feet of Anthony Knockaert. Sent in the corner which Roberto Pereyra superbly volleyed home to give Watford the lead.
Etienne Capoue -7
Solid in the middle of the park and some lovely touches at times.
Roberto Pereyra -9
Showed some lovely skill. Lively. Stunning strike and great technique for the opening goal and cool finish for his second. Man of the match.
Will Hughes -8
Always a nuisance. Half-volleyed a decent opening wide in the first half.
Abdoulaye Doucoure -7
Wasted early break away opportunity when the hosts broke quickly from an Albion corner. Hard-worker in central midfield.
Andre Gray -7
Stung the palms of Ryan early on. Clever movement throughout.
Troy Deeney -6
Missed a great chance on 17 minutes when Pereyra's blocked shot fell to him eight yards out but he was denied by Mathew Ryan. A handful.
Subs (all sent on in closing stages):
Isaac Success -6
Ken Sema -6
Kiko Femenia -6
Mathew Ryan -6
Kept out fierce effort from Gray early on and then produced outstanding save to keep out Deeney's close-range shot. Little chance for either Pereyra goal.
Sent in one teasing delivery, which was volleyed wide by Dale Stephens. Forced off with a hamstring injury midway through the first half.
Shane Duffy -6
Dominant in the air as usual. Deeney and Gray proved a handful for Albion's defence.
Lewis Dunk -7
Early challenge denied Pereyra a shot at goal. Composed as always. Albion's best player.
Made his Albion after joining from RB Leipzig in the summer. Lost possession early on, which luckily went unpunished as Watford broke quickly. Switched from left-back to right-back midway through the first half.
Anthony Knockaert -5
Booed throughout by the Watford fans again. Penalty shout waved away midway through the first half. Gave the ball away for Watford's second goal.
Dale Stephens -6
Excellent tackle on Pereyra early on. Didn't score in the Premier League last season but volleyed Bruno cross wide on 21 minutes. Booked.
Davy Propper -6
One of the Dutch midfielder's quieter days. Headed a Alireza Jahanbakhsh corner over in the second half.
Solly March -6
Nice run early on to win a corner but faded as the game went on. Subbed with 18 minutes to go.
Pascal Gross -5
Worked hard but Albion did not get the ball to their influential playmaker as much as they would have liked. Subbed after an hour.
Glenn Murray -5
Saw little of the ball. Limited service for the frontman this afternoon.
Gaetan Bong -6
Came on midway through the first half for Bruno. Solid game after coming on early in the first half.
Yves Bissouma -7
Replaced Pascal Gross on the hour. Free kick high and wide from 25 yards and shot another opening wide. Lively performance.
Alireza Jahanbakhsh -6
Came on 18 minutes from time and threatened straight away as his low cross was claimed by Foster.