Three second half goals from Sanchez, Giroud and Ramsey helped in-form Arsenal overcome an impressive Watford side who can take plenty of positives from a fine first hour.
The hornets were good for 65 minutes in which they held their own and created a lot of chances but the Gunners quality made the difference in a final half-hour in which they scored three quick-fire goals to take all three points.
It could have been all different however and Watford will rue missed opportunities. The Golden Boys might have led at half-time had Odion Ighalo converted the best chance of the half.
The Hornets’ Head Coach Quique Sanchez Flores named an unchanged starting line-up following the 1-1 draw at Bournemouth a fortnight ago.
Alexis Sanchez tested Heurelho Gomes in Watford goal twice in the opening ten minutes.
But the hosts where not just going to lie down and get rolled over. Deeney had Watford’s first chance soon after, outmuscling Gunners midfielder Francis Coquelin 25 yards from goal, but his well-hit right-footed effort from just outside the box was palmed away by Petr Cech.
The Hornets had a great chance to take the lead in the 19th minute when Deeney raced clear unopposed down the left-hand side, but his squared pass was turned behind by Koscielny, with Ighalo lurking and ready to convert in the middle.
Ramsey should have scored with 30 minutes played when he ghosted in to meet a chipped Alexis cross at the back post, but his first-time volley went over the bar, much to the relief of the Hornets’ defence.
Watford responded with a great chance of their own.
Ighalo was sent racing clear by Anya’s through ball but the usually clinical front-man scuffed his shot wide of the target, with only Cech to beat.
With the opening half ending scoreless, Arsenal stepped up the tempo in the second half and with 62 minutes on the clock, the Gunners counter-attacked and Cazorla picked out Mesut Ozil in the box and Alexis was on hand to slam the loose ball past Gomes off the upright.
The deficit was doubled five minutes later when Ozil centred for substitute Giroud to fire into the roof of the net just four minutes after his introduction for Theo Walcott.
Ramsey soon made it 3-0 to the visitors, finishing Bellerin’s mazy run from only 12 yards out.
Giroud could have claimed another goal but was denied by a fine Gomes save.
And in the last minute of the game, Ighalo chested down a return ball for Deeney for the Watford skipper to attempt the half-volley, but it bounced kindly for Cech, who gathered the game’s final chance with relative ease.
Ighalo and Watford next face a trip to Stoke City.