Watford’s unbeaten start to the season was spectacularly ripped up as they were on the receiving end of a footballing lesson and a footballing exhibition at times as what could be an exceptional Manchester City team cantered to a 6-0 victory.

The Hornets were able to live with their big-spending opponents for the first 27 minutes – and spurned a good chance to take the lead when Richarlison headed wide – only to be blitzed by a three-goal goal in 10 minutes at the end of the first half.

City were aided by a couple of dubious offside-looking goals but the Hornets' makeshift defence was unable to deal with the pace, power and invention as Sergio Aguero, twice, and Gabriel Jesus scored the goals which effectively ensured Pep Guardiola’s side would be top of the Premier League by half-time.

The Hornets looked to be positive after the break while their opponents were relatively content to sit on their lot, although another good attacking spell was to end with Nicolas Otamendi heading in number four.

Substitute Etienne Capoue wasted a good chance to give Watford a goal for their efforts before the goal machine that is Aguero completed his hat-trick with nine minutes were remaining.

But a very tough afternoon didn’t end there for the Hornets as Raheem Sterling made it six from the penalty spot after being fouled by Christian Kabasele as the visitors made it 15 goals in three games in the space of a week.

Marco Silva made the two expected changes from the team that made it four games unbeaten at the start of the season with a 2-0 victory at Southampton last weekend, as Daryl Janmaat and Adrian Mariappa came in for the injured Kiko Femenia and Younes Kaboul.

Deadline Day arrivals Molla Wague and Marvin Zeegelaar were on the bench for the first time to provide alternatives for the defensively-stretched Hornets, but there was some positive injury news among the substitutes with the return of the fit-again Roberto Pereyra.

Despite having played on Wednesday when they eased to a 4-0 Champions League victory at Feyenoord, Pep Guardiola opted to make just the one change to his starting line-up with Sterling coming in for Bernardo Silva in a bold 4-1-3-2 formation.

And it was the visitors who were immediately on the attack from the kick-off; the ball being worked across the backline and down the right to Kyle Walker, who slipped in Sterling on the right side of the area and he cut the ball back for Aguero, but Kabasele was able to get across the Argentine star to concede a corner.

Watford were also looking to be positive in the early stages though; Richarlison attacking on the counter before his advances were curtailed by Walker, while John Stones also had to move swiftly to prevent Andre Gray using his pace to get on the end of a pass out of defence.

City’s next opening was to come from a Kevin De Bruyne corner from the right which Fernandinho headed over at the near post, before Benjamin Mendy fired high and wide from distance.

The visitors were looking for the early breakthrough and they should have had another opening when David Silva’s fine cross-field ball was knocked back into the path of Sterling first time by De Bruyne from the right side of the area, but the England international could only kick fresh air. However, City kept the attack alive and Fernandinho was able to have a crack from 25 yards, but Heurelho Gomes was right behind the low strike.

Vicarage Road then found itself beneath a deluge, but as the rain abated in the 14th minute the Hornets had their first effort of the afternoon when Abdoulaye Doucoure’s mis-hit strike from the edge of the area was deflected a yard or so wide of Ederson’s right-hand post by a yellow-shirted teammate.

The Hornets’ decision-making had to spot on given the calibre of the opposition of Nathaniel Chalobah chose the wrong one when he tried to take on one opponent too many in midfield and the resulting pass in behind would have put Sterling in had it not been for a fine tackle from Kabasele.

Another mistake between Janmaat and Doucoue gave Aguero the opportunity to come in and advance from the right, but his curled effort was deflected behind.

The Hornets right-back was to then require treatment when he was caught by Otamendi after making a superb defensive far-post header. But as the Dutchman jogged back onto the pitch, Watford spurned a good chance to take the lead.

Jose Holebas created the situation with an inswinging free-kick from the left and Richarlison got between the City defenders, but headed down and wide of the far post.

The significance of that miss was magnified soon after when City took the lead from a set-piece of their own, De Bryune clipping in a free-kick from right of centre and Aguero getting first run on the defence to head home and score, as he so often does, against the Hornets.

And that one-goal lead was to doubled less than four minutes later when the ball was worked to David Silva on the left side of the six-yard box and he slipped it across to present Aguero with the simplest of goals for his second.

After De Bryune had fired at Gomes, a bad end to the half was to get even worse for the Hornets when Aguero turned supplier, sliding the ball down the side of the defence for the offside-looking Jesus to run in behind and fire across Gomes and into the far corner to make it 3-0.

Doucoure was to pick up the game’s second yellow card in the 40th minute for pulling back Sterling after Holebas had been booked earlier, but De Bruyne spared the Hornets further punishment by curling his free-kick from 25 yards over the top.

Watford may have been facing a mountainous-sized task but they started the second half in a positive vein and had the first chance; Holebas seeing his cross from the left half-cleared to the edge of the area where Andre Carrillo hit a first-time half-volley across the face of goal and wide of Ederson’s back post.

Carrillo had spent much of the first half having to defend but he again caught the eye going forward in the 52nd minute, twisting and turning tight to the byline to force a corner off Stones. That set piece was taken by Tom Cleverley and resulted in Chalobah getting caught in the penalty area, but referee Anthony Taylor did not see it as a foul and allowed play to continue which resulted in Aguero shooting wide.

The home side continued to be progressive and had another effort on the hour when Richarlison headed over Holebas’ inswinging corner from the left.

The City threat remained though, and soon after Mendy fizzed in a dangerous low ball from the left which went right across the six-yard box before it went out from a corner. From De Bryune’s set-piece from the right, Otamendi saw his effort bounce over off the top of the crossbar.

The visitors continued to press, with Silva warming Gomes’ gloves with a rising drive from the left side of the area, before they made it 4-0 when the diminutive Spaniard exchanged passes with De Bruyne on the left before whipping in a cross which Otamendi headed down and into the net.

Both sides were already planning a change and they were made before play restarted; Bernardo Silva replacing Jesus while Pereyra made his return from injury in place of Cleverley. A second City change followed soon after as Ilkay Gundogan came on for De Bryune.

Chalobah made way for Etienne Capoue in the 70th minute and it was the Frenchman who missed a great chance to pull one back, heading over at the far post after a corner from the right had been heading on.

Marco Silva completed his changes by bringing on Troy Deeney for Gray, while David Silva was to make way for Leroy Sane.

The game may have had a different feel to it to the 5-0 thumping dished out by City last season, but the score was to be the same in the 81st minute when Aguero received the ball and showed his qualities once again by jinking through the defence to slide the ball past Gomes and complete his hat-trick in off the far post.

It was almost six when Mendy’s low cross from the left was just about kept out by Holebas, who nicked the ball away from Aguero despite getting his legs mixed up. But the reprieve was to be short-lived as Kabasele tripped Sterling in the box and the City winger sent the spot-kick high to Gomes’ right to complete a highly impressive afternoon’s work by the visitors.

Watford: Gomes; Janmaat, Mariappa, Kabasele, Holebas; Doucoure, Chalobah (Capoue 70); Carrillo, Cleverley (Pereyra 64), Richarlison, Gray (Deeney 74). Not used: Karnezis, Success, Wague, Zeegelaar.

Manchester City: Ederson; Walker, Otamendi, Stones, Mendy; Fernandinho; Sterling, De Bruyne (Gundogan 66), D Silva (Sane 77); Aguero, Jesus (B Silva 64). Not used: Bravo, Danilo, Mangala, Delph.

Bookings: Holebas for a foul (29); Doucoure for a foul (40).

Attendance: 20,305 (2,086 away fans).

Referee: Anthony Taylor.