Match ends, Sheffield Wednesday 0, Watford 3.
Watford moved to the top of the table as they gave new boss Slavisa Jokanovic a winning start at Hillsborough.
Odion Ighalo put them in front with a comfortable finish after Matej Vydra was adjudged onside by the linesman.
And they were gifted a second when Owls keeper Keiren Westwood let Almen Abdi's curling shot slip through his fingers.
Sub Royston Drenthe forced two fine saves from Watford's Heurelho Gomes after the break, but the visitors sealed it with Vydra's superb finish.
The 22-year-old lifted the ball over Westwood for his fifth of the season from a pass by Juan Carlos Paredes just seconds after the Ecuadorian was introduced by Jokanovic as a replacement for Fernando Forestieri, who had earlier hit the post with a low shot.
|Vydra has now scored 27 goals in 59 games in his two loan spells for Watford from Udinese, either side of a season at West Brom|
Both managers had rung the changes before kick-off with Jokanovic naming debutant Sebastien Bassong, Daniel Pudil, Forestieri and Ighalo in his first starting line-up for the Hornets.
The return of Sam Hutchinson after a back problem was good news for Wednesday, but his first game since 19 August lasted only seven minutes before he had to limp off with a new injury.
Watford were slicker in thought and deed and although it was touch and go whether Vydra was onside before teeing up Ighalo, they were deservedly in front at the interval.
The introduction of Drenthe perked up Wednesday and Gary Madine headed a chance over the bar just moments after Jacques Maghoma's powerful drive was beaten away by Gomes.
He did even better to keep out two powerful left-footed efforts from Drenthe, but Vydra's goal killed off any hopes of a comeback by the Owls as Watford extended their unbeaten run to six matches.
Glenn Loovens went close to a late consolation as his header from Drenthe's corner hit the post.
Sheffield Wednesday boss Stuart Gray:
"I have seen their first goal and the boy is blatantly offside.
"As soon as he put the ball through I thought the linesman was just going to stick his flag up and I think 10,000 fans appealed at the same time.
"Unusually Keiren Westwood made an error for the second goal and that is probably the only mistake he has made since he has been at this football club.
"I said to the players at half-time that you are going to have setbacks, so we went into the second half trying to play but we came up against one of the best teams in the Championship today."
Watford head coach Slavisa Jokanovic:
"It is definitely a great day for us, but this league is very tough so we have to try to improve and control games as well as we have today.
"We can stay top of the league, but it will be tough. It was important for us to have good offensive players today, but everyone defended brilliantly.
"We played with three strikers today and they understood what we wanted, finding the gaps and playing very well.
"I am very happy and the team must be very happy."
- 28HopeSubstituted forDrentheat 45'minutesBooked at 88mins
- 20LeeSubstituted forNuhiuat 68'minutes
- 4HutchinsonSubstituted forSemedoat 7'minutes
- 12DoyleyBooked at 44mins
- 39Bassong Nguena
- 18PudilBooked at 55mins
- 22AbdiSubstituted forDyerat 79'minutes
- 11ForestieriSubstituted forParedesat 68'minutes
- 24IghaloSubstituted forDeeneyat 81'minutes
- Jeremy Simpson
- Shots on Target
Second Half ends, Sheffield Wednesday 0, Watford 3.
Corner, Sheffield Wednesday. Conceded by Sebastien Bassong.
Corner, Sheffield Wednesday. Conceded by Joel Ekstrand.
Attempt blocked. Tom Lees (Sheffield Wednesday) header from the centre of the box is blocked.
Glenn Loovens (Sheffield Wednesday) hits the left post with a header from the centre of the box. Assisted by Royston Drenthe with a cross following a corner.
Corner, Sheffield Wednesday. Conceded by Daniel Tözsér.
Attempt blocked. Stevie May (Sheffield Wednesday) right footed shot from outside the box is blocked. Assisted by Royston Drenthe.
Juan Carlos Paredes (Watford) wins a free kick in the defensive half.
Foul by Stevie May (Sheffield Wednesday).
Attempt blocked. Atdhe Nuhiu (Sheffield Wednesday) right footed shot from outside the box is blocked.
Attempt blocked. Jacques Maghoma (Sheffield Wednesday) left footed shot from outside the box is blocked. Assisted by Glenn Loovens.
Royston Drenthe (Sheffield Wednesday) is shown the yellow card.
Royston Drenthe (Sheffield Wednesday) has gone down, but that's a dive.
Offside, Sheffield Wednesday. Liam Palmer tries a through ball, but Atdhe Nuhiu is caught offside.
Attempt missed. Gary Madine (Sheffield Wednesday) header from the centre of the box is too high. Assisted by Jacques Maghoma with a cross.
Corner, Sheffield Wednesday. Conceded by Heurelho Gomes.
Substitution, Watford. Troy Deeney replaces Odion Ighalo.
Offside, Watford. Daniel Pudil tries a through ball, but Odion Ighalo is caught offside.
Gianni Munari (Watford) wins a free kick in the defensive half.