Son Heung-Min settled the game with a looping free-kick at the end of the first half, catching Watford goalkeeper Daniel Bachmann out.
The away side went closest first, counter-attacking within the opening minute to have Juraj Kucka's shot cleared off the line by Eric Dier. An even first-half in the midfield was nearly broken by Japhet Tanganga's scuffed shot in a goal-mouth scramble, before Son scored the game's only goal.
Spurs were by far the more professional in the second-half, and could have won the game by more had it not been for some relatively solid defending from the Hornets.
Tottenham have now solidified themselves at the top of the Premier League; now the only side to have a perfect record after three games. Watford, meanwhile, sit 12th and have failed to open their goal-scoring account away from Vicarage Road.
Hornets lack clinical nature
Xisco Munoz, Watford manager, said pre-match that it was his hope that his team will "give all its best from the first minute until the last minute of the game". He would have been pleasantly surprised, then, when Kucka nearly gave Watford a very early lead in North London.
Indeed, throughout the first half, the Hornets managed to run a decent counter-attacking game against Spurs. Kucka and Emmanuel Dennis, two new signings, managed to play some nice football down the left-side whilst Ismaila Sarrlooked threatening on the right. Joshua King, another new purchase, conducted some decent hold-up play.
Although their attacking intent was good to watch at points, certainly much better than in their 2-0 defeat at Brighton and Hove Albion, they still lack the final product. This was more frequent in the second half, with Peter Etebo, Moussa Sissoko and Sarr failing to test Hugo Lloris with their shots.
In games of this nature, it is in these circumstances where the final finishing touch is needed to get something out of the game. That being said, the Hornets were much stronger when they did go forward and pressed well in the first-half. There would have certainly been hope on the benches that they may have gone back to Hertfordshire with something to show for their efforts in the opening forty-five minutes.
Tottenham looking defensively sound and sleek in the midfield
Although early days, Tottenham have again shown promise at the opening of the 2021-22 Premier League season.
Three consecutive 1-0 victories - against Manchester City and Wolverhampton Wanderers prior to Sunday's win - demonstrate that their defence is looking surprisingly solid. This gives Nuno Espirito Santo, who arrived from Wolves in the Summer, a basis to be optimistic about for the season.
Indeed, if the defence continues to operate nicely, then Spurs may threaten more than what is expected of them. Son was the stand-out player, but Dele and Steven Bergwijn had good games going forward, with Pierre-Emile Hojbjerg holding play up nicely in the midfield. Harry Kane had a rare quiet game in his first start for the club this season - yet, with the high possibility that he does find form, Spurs could look a genuinely dangerous outfit. For their opposition, every chance will count.
Could Watford have been more optimistic?
Although the Hertfordshire outfit threatened nicely on the counter and had good passages, far too often the team sat too deep and failed to truly test Lloris and the Spurs defence.
Whilst the Tottenham back-line is looking notably stronger and more resistant this season, it is not impossible to see how it could be undone. Man City dominated in their 1-0 defeat at the Tottenham Hotspur Stadium - Watford could have attempted to attack more, instead of seemingly passing back at many an opportunity when the counter-attack was off. This was especially the case in the second-half.
Ahead of three games against what looks like evenly matched opposition after the international break - Wolves, Norwich City and Newcastle United - Munoz should set his team up positively and ready to attack, more like they were in their opening day victory against Aston Villa.
Either way, Munoz and the Hornets will take many a positive note from a game which could have perhaps earned them a point had they been more optimistic and clinical when opportunities arose. For Tottenham, they will look to maintain their 100% start after the break against Crystal Palace, with Nuno also taking rest with plenty to be pleased about.