It had to be better, it had to be a victory.

Watford finally pieced together a performance that earned a relatively comfortable success, only their second in 10 games - encouraging, uplifting and something upon which to build after a miserable few weeks.

Sticking with 3-5-2, the Hornets also had pattern to their play. They seemed to know where their teammates were, players wanted to be on the ball and possession was turned into chances.

The boost of an early goal removed any nerves, and when Davis ended his own personal barren run in front of goal with a cracker after 15 minutes the Hornets had a platform for a thoroughly dominant first half.

Birmingham rallied after half time and should have pulled one back, but Watford emerged from a tricky period to resume control and then kill the game off with little more than 15 minutes to go.

It was by no means perfect, but Watford looked more assured than they have in a long time, moving the ball around with alacrity and showing for each other.

Out of possession they chased back well and got back into shape quickly. There was a clear desire to work hard and get the ball back.

However, the most obvious step forward was in the final third, where Watford had shots, chose good passes, and posed a threat.

Having two strikers made a tangible difference, Davis benefitting from having Pedro close by and the two of them never allowed the Birmingham defence any comfort.

There were some unexpected stars - Bacuna stepped up to the plate and hit the ground running after barely playing of late, giving his best performance since joining.

Alongside him Kone showed some moments of real class, while Ngakia was another who returned to action and slipped in seamlessly, displaying the ability to do both halves of the wing-back role.

Having been so poor at Rangers on Saturday, Watford had to be better and Wilder will have been heartened by tonight.

Now the next step is to build on this and put another similar or better showing in against Wigan on Saturday.

Only once this season have the Hornets won more than a single game. To keep the season alive, they have to complete back-to-back victories on Saturday.

Wilder made three changes: Choudhury (suspended) and Sarr (injured) missed out totally, while Gaspar dropped to the bench. In came Ngakia, Kone and Bacuna.

Watford made the ideal start by going ahead in the fifth minute. Davis played the ball to Sema in acres of space on the left, he drilled a low cross and Louza turned it into the net from the edge of the six-yard box.

Ten minutes later it was 2-0, and if you’re going to end your goal drought then this was the way to do it.

Porteous broke up play and released Louza through the centre. The midfielder drove forward and then slid the ball to Davis on his left, who took on Long inside the box before smashing a shot from a tight angle into the roof of the net.

There was so nearly a glorious third after 22 minutes as Ngakia gathered a clearance 25 yards out, and immediately left fly with a shot that kept rising and had Ruddy beaten, but hit the top of the far post

Five minutes later another excellent move started by a sublime back-heel from Sema saw Pedro tee up Kone for a low drive from 20 yards that flew narrowly wide with Ruddy beaten.

In the 34th minute Louza's corner from the right was met by Cathcart who rose highest in a crowd but headed wide of the back post.

Right on the stroke of half time a great dummy and burst of pace from Ngakia saw him cut in from the flank and then slide a pass into Davis. The striker jinked past a tackle but his touch was just too heavy and the ball was cleared as he was trying to get a shot away.

A minute into the second half and Pedro’s clever footwork on the edge of the box made space but he shot straight at Ruddy

Seconds later came the first chance of the game for Birmingham and they should have done better. Graham sent sub Hogan through the middle but with only Bachmann to beat he rolled his shot wide.

Then a quick free kick rolled into Bielek's feet in the box allowed him to turn, but his shot was straight at Bachmann

In the 52nd minute there was a great chance for Birmingham. Graham crossed from the left and Trusty got between defenders inside the box but ballooned his shot wide from less than six yards.

Watford had to ride out a bright first 15 minutes of the second period for Birmingham, but once they had they looked in control again.

The third goal, which killed the game off, came after 73 minutes and it was a first for the club for Assombalonga.

Kone broke away down the right after a fine pass from Gaspar. The Canadian beat Mejbri and then played a low cross which Assombalonga bundled into the net from close range.

That goal came 4,014 days after Assombalonga made his Watford debut, setting a new club record for the gap between first appearance and first goal.

Watford: Bachmann, Ngakia (Gaspar 65), Louza, Davis (Assombalonga 65), Pedro (Asprilla 80), Kone (Morris 90), Sema, Cathcart, Porteous, Bacuna, Hoedt. Subs: Hamer, Araujo, Kabasele