Boro were beaten on Teesside as a goal five minutes before half-time handed Watford the points.
The hosts battled for an equaliser and ratted the post in the second half through Rav van den Berg, but there would be no reprieve.
Possession
42%Shots
14Shots On Target
6Corners
4Fouls
72
0
Cards
2
0
Boro began on the front foot, dominating possession and forcing Watford deep inside their own half.
There was an early penalty shout when Dan Barlaser won the ball high up the field and it broke to Tommy Conway, whose low strike was saved by Egil Selvik.
Kelechi Iheanacho had a shot deflected wide and Morgan Whittaker was denied by Selvik as Boro aimed to increase the pressure.
Watford improved and two Edo Kayembe efforts threatened the Boro goal before the away side went in front five minutes before half-time.
Imran Louza’s corner from the right was headed in by Moussa Sissoko from close range to hand the Hornets the advantage.
Middlesbrough: Travers, Ayling (Dijksteel 59'), van den Berg, Edmundson, Neto Borges (Forss 79'), Whittaker (Iling-Junior 67'), Barlaser (Burgzorg 45'), Morris, Hackney, Iheanacho (Azaz 58'), Conway
Subs: Burgzorg, Dijksteel, Azaz, Forss, Glover, Giles, Iling-Junior, Dede, McCabe
Watford: Selvik, Andrews (Ngakia 80'), Keben, Abankwah, Larouci, Louza, Dele-Bashiru, Sissoko (Ince 45'), Kayembe, Chakvetadze, Doumbia (Vata 65')
Subs: Ngakia, Sierralta, Pollock, Ince, Vata, Morris, Bond, Adu-Poku, Nabizada
Delano Burgzorg was introduced at half-time by Boro and there was an early sight of goal when Conway’s strike was deflected onto the roof of the net.
A pair of Mark Travers saves from Georgi Chakvetadze kept the deficit at one and allowed the Teessiders the opportunity to search for an equaliser.
A dangerous cross from substitute Finn Azaz was palmed away by Selvik and just out of the reach of Conway.
Neto Borges then found Whittaker with a deep cross and he played it back to Burgzorg, who dragged wide from 12 yards.
Another Burgzorg strike was clawed away by Selvik, who also denied the Boro No.10 with a near post save.
The resulting corner saw a Rav van den Berg header hit the post as Boro continued to be frustrated in their efforts for a leveller.
That frustration continued until the final whistle as Watford saw it out to secure all three points.
