Sean Longstaff's stunner gave The Magpies a deserved lead midway though the first half, but they were made to rue their missed chances when Ismaila Sarr levelled matters in the 72nd minute.
Newcastle could have played all day and not scored a second
Newcastle supporters will be scratching their heads as to how their side failed to win on Saturday afternoon.
It seems typical that it took a screamer to break the deadlock, when they couldn't finish off the much more simpler opportunities they had in the game.
As much as Longstaff's goal was brilliant, he is also one name mentioned for missing a huge chance when Allan Saint-Maximin picked up on a poor back-pass before squaring to the Geordie midfielder who could only fire over from inside the area.
Also guilty of missing great opportunities were Joe Willock and Miguel Almiron, as well as Saint-Maximin.
But the worst of the lot has to go to Jacob Murphy who found himself one-on-one with Ben Foster in the dying moments. He had the full goal to aim at but could only chip the ball into the hands of the home sides' goalkeeper.
Newcastle should have been out of sight but they also could easily have lost the game late on themselves. Fortunately VAR came to the rescue to rule out Josh King's late strike for offside.
It's fair to say that United haven't been the most clinical of sides in recent seasons and their Achilles heal proved costly yet again on Saturday afternoon.
Tactical changes still don't give Newcastle a first win
Having started the season with a five-at-the-back formation, Steve Bruce opted to change to a back four against The Hornets.
This switch in formation was essentially triggered during last weekend's draw with Leeds United after it brought about a much-improved second half display in another game that ended 1-1.
The change does appear to have allowed Newcastle to create more chances, but their defensive fortunes didn't change as they failed to defend a set-piece which Sarr profited from. The Watford attacker isn't exactly known for his heading ability but it was criminal to leave him unmarked at the back post.
An improved performance but Steve Bruce is still not popular
It didn't take long for the first anti-Bruce chant to be sung at Vicarage Road.
In fact, the game hadn't even kicked off by the time the first shouts for Bruce to go were heard from the away end.
It was even noticeable when Newcastle had a deserved 1-0 lead. It was almost as if they knew that they wouldn't traveling back to the North-East on the back of their first win of the season. They would be proven correct.
In fairness, the fans did continue to back their side throughout the game but there is no way of hiding the discontent amongst the Newcastle fanbase.
A much-improved Sean Longstaff
Since Rafa Benitez's departure from St James' Park in 2019, Longstaff seems to have been a player whose performances have dipped.
Benitez was the man who gave the midfielder his chance after being sent out on a couple of loan spells, and he repaid the Spaniard's faith by putting in some excellent performances.
Longstaff's return to the team has come in unfortunate circumstances with Jonjo Shelvey being sidelined, however he will now be hoping to perform on a consistent basis and if he can rediscover his form from the second half of the 2018/19 season, his creativity could prove highly beneficial to The Magpies.