When many Watford fans headed, understandably, for the exits early to start the long journey back to Hertfordshire, they may have spotted the Hornets’ automatic promotion hopes disappearing over the horizon ahead of them.

Catching the top two was going to require a superhuman effort anyway: to lose so timidly and haplessly against one of your promotion rivals was almost the textbook ‘what not to do’ in that situation.

The first half was as bad as it was embarrassing. The home side pulled Watford all over the place, and when they took a break from doing that the Hornets caused their own problems.

Poor passing, erroneous clearances, players running into each other or being caught in possession – the full gambit of calamities rolled into one grim afternoon.

To be fair to Boro, they were good and they stretched Watford. However, how much of this result was the home side being very good or Watford just performing especially badly was hard to tell.

The second half was a non-event: the Hornets never threatened and the home side merely had to go through the motions.

Had they been a bit more clinical, they would have scored more. The fact it mattered not a jot shows just far short Watford fell of making a game of it.

So often this season the travelling fans have been served up some proper dirge and this time they had to travel further than usual to receive their footballing version of a plate of gruel.

There were no saving graces or bright spots. This was a sound beating that may have been by two goals but, in terms of the game, the gap was far wider.

Another hamstring injury, to Paolo Ferreira, only added to the woes and even though some of those who have been out are due to return, it’s hard to see that anything other than 15 wins or more will get Watford near the top two – and having witnessed today, that just doesn’t look even remotely like happening.

The Hornets made two changes with Davis returning to lead the line while Kamara was back in the starting XI. New loan signing Araujo was on the bench.

Watford were slow out of the blocks and were given a warning after two minutes as Archer found space in the box. His shot was blocked and Akpom's follow-up was deflected over the bar.

Watford should have done better in the seventh minute as Ferreira sent Kamara away through the middle and the wing back had options either side. However he delayed his pass and was tackled just outside the box.

In the 12th minute Giles' curling cross from the left had to be headed wide by Cathcart in a crowded six-yard box, and two minutes later Akpom released Forss on the right of the box and his firm shot was blocked by Bachmann.

Soon after a cross was deflected to Archer, and his shot was cleared from near the line by Choudhury.

Then in a rare foray forward by Watford, Sarr curled a shot over from 20 yards.

The Hornets wasted a great chance in the 26th minute. Davis steered a pass into the path of Martins and he surged into the Boro box. Keeper Steffen came out but Martins put his shot high and wide.

A couple of minutes later there was a let-off for Steffen as he delayed and delayed while trying to pass out from the back and Sarr dashed in. The forward got a foot to the ball but it span to safety.

Boro started to get back on top and in the 32nd minute Archer turned Sierralta inside out and sent a shot towards the far corner, but Bachmann got down and made a fine stop.

The home side went ahead in the 35th minute and Kamara will not be proud of his part. A long ball out of defence from a Watford free kick put Archer and Kamara in a foot race. The Watford defender looked favourite but Archer nicked the ball away and raced into the Watford box. Bachmann did well to block his shot but the ball span up and Akpom headed past Kamara on the line.

Defensively the Hornets were looking very rocky, and shortly after the goal Kone lost the ball 25 yards out, it ran into Archer's path and Bachmann had to dash off his line to block. The ball ran loose and Cathcart had to bundle it wide to stop Akpom reaching it.

Then another let-off. Choudhury and Sierralta went for the same high ball in the centre circle and neither got it. Archer broke into the Watford box but Cathcart did enough to force him wide and then block his shot.

However, the defensive frailties told again as Boro added a second in first-half stoppage time.

A low pass into the box seemed to be covered but it ran past Sierralta and straight to Forss. He still had two men between him and Bachmann but he moved to one side and then rolled a shot into the corner.

Bilic made three changes at the break, sending on Araujo, Adeyemo and Bacuna to replace Davis, Sierralta and Kone.

The Hornets went to 4-2-3-1: Choudhury at centre back with Cathcart, Ferreira and Kamara the full backs. Gaspar and Bacuna holding, Sarr and Martins wide, Adeyemo in behind Araujo.

The on-loan striker’s first touch in English football forced a smart block from Steffen, but that was a false dawn as rarely did Watford look dangerous.

Steffen again deliberated on a clearance and then gave the ball to Martins. His cross was half cleared and Adeyemo thumped a shot over the bar, but really the Hornets were feeding off scraps.

In the 58th minute Akpom and Archer combined to give Giles a shooting chance on the left but he sent it straight at Bachmann.

Just after the hour mark Ferreira pulled up as he went down the flank. He grasped the back of his leg and limped off – the almost requisite new hamstring injury.

Six minutes McGree was perfectly positioned to meet a deep cross at the back post but rather than head at goal he tried to nod it square and the chance was gone.

Then Hackney jinked his way into the box and hit a shot that Bachmann parried. The ball then played ping pong before being hacked clear.

Boro didn't seem to want a third as in their next attack a deep cross found two of them unmarked at the back post, but McNair shanked his shot wide.

Adeyemo saw a shot saved by Steffen and Bachman held a curling from McGree but the game petered out tamely with the visitors never remotely looking like threatening the home side.

Watford: Bachmann; Ferreira (Asprilla 61), Sierralta (Bacuna ht), Cathcart, Kamara; Gaspar, Choudhury, Kone (Adeyemo ht); Martins (Pollock 70), Davis (Araujo ht), Sarr. Subs