Watford further boosted their hopes of automatic promotion and moved back to third in the table with another excellent showing on their travels as they thrashed Birmingham City 4-0 at St Andrew’s.

The Hornets were comfortably the more dangerous side in the first half and Troy Deeney, Almen Abdi and Matej Vydra all had opportunities to make the breakthrough before Deeney headed in an Ikechi Anya cross in the 38th minute.

Anya then doubled the lead a minute before the break when after being given the freedom of the right side, he came inside and showed quick feet to fire past Jack Butland.

The visitors had to withstand a few edgy moments at the start of the second half as the Blues sought a way back into the contest but 17 minutes after the restart the points were effectively already heading back down the M6 and M1 as Deeney tucked away his second at the end of the Hornets’ latest devastating counter-attacking move.

It was left to Abdi to complete another very pleasing afternoon’s work when he fired home the fourth from the edge of the area with two minutes remaining as the Hornets made it nine wins on the road this season and sent their superb travelling 2,454-strong support home very happy.

Gianfranco Zola made three changes from the side that drew 2-2 with Crystal Palace as the Hornets went into the game with their defensive resources somewhat stretched.

Joel Ekstrand was still sidelined with a knee problem and he was joined in the treatment room by Tommie Hoban and Fitz Hall. This meant Marco Cassetti moved back into defence, alongside Nyron Nosworthy, who missed the last match as he was returning from international duty with Jamaica. Cassetti’s enforced change of position saw Anya come in at right wing-back, while Cristian Battocchio was preferred to Jonathan Hogg in the centre of the park.

Birmingham also drew their last outing, 1-1 at Charlton Athletic, and boss Lee Clark made two changes to his line-up.

Vicarage Road old boy and top scorer Marlon King was ruled out through injury, while Callum Reilly dropped to the bench. Their places went to the new-look strike partnership of Wes Thomas and Peter Lovenkrands, while another familiar face, Paul Robinson, was also in the starting line-up.

Interestingly, Cassetti started on the left side of the central defensive trio but it was his team who had the first opening after a minute when Deeney latched on to a poor Morgaro Gomis pass and drove at the defence, beating Steven Caldwell on the outside but as the striker got to the by-line to the right of goal, he sliced a shot from an acute angle behind.

The visitors had the better of the opening exchanges and had the first on-target effort of the afternoon when Butland dropped to his right to hold an Anya drive from a Vydra pass after good work by Deeney, who had made a lively start against the team he supports.

Birmingham’s first effort came in the 12th minute when Gomis fired harmlessly high and wide from distance. But six minutes later came perhaps one of least surprising outcomes of the match when Robinson was rightly booked for a late challenge on Abdi, leaving the Hornets favourite the prospect of coping with the pace of Anya for the next 70 or so minutes on a booking.

Watford continued to be in the ascendency though, and Vydra had the next effort when he curled a right-footed shot over from 20 yards before the Czech striker saw another strike from outside the area deflected behind. From Abdi’s resultant corner on the left, the Hornets were inches away from taking the lead as Deeney glanced a downward header narrowly wide of the far post.

Zola’s men went close again in the 25th minute when after some playing some neat keep ball near their left-hand corner flag, Battocchio spread a cross-field ball out to Anya. He took on and beat Robinson on the outside before laying the ball inside to Vydra, who hit a right-footed half-volley on the turn which was straight at Butland and the keeper managed to grab the ball at the second attempt as Deeney closed in.

Chris Burke threatened to unhinge the Hornets backline when he attacked the right side of the penalty area and left Daniel Pudil on the ground but the winger’s low delivery was put behind for a corner. But Watford were soon testing Butland again as the England international did well to keep out a firmly struck Abdi shot from the left side of the area after Vydra had laid a Pudil ball from the left into the Swiss midfielder.

Butland had to be alert again in the 33rd minute to deal with a Vydra free-kick from close to 30 yards, although the keeper was not unduly tested. However, Clark’s side then had a decent little spell which saw Nosworthy forced to head behind a dangerous Caldwell header and Manuel Almunia deal with an awkward free-kick before Thomas did well to cut back on his left foot on the edge of the area before curling a shot over.

But the goal Watford had been threatening did arrive in the 38th minute and it would have given the scorer particular pleasure.

Nathaniel Chalobah and Abdi combined in midfield and found Anya on the right and he delivered a pin-point cross for Deeney to rise and plant a header down and beyond Butland to make it 1-0 with his 13th of the campaign.

Anya almost created another opening three minutes later when he was again picked out by Abdi in plenty of space but his delivery was too close to the Blues keeper on this occasion, although Deeney was again waiting to pounce.

But Anya was to make no mistake the next time he received the ball a minute before the interval.

The space the winger initially had after receiving Chalobah’s pass was bordering on the ridiculous but after coming inside and looking for an passing opportunity, he toyed with the Birmingham defence before showing quick feet and slamming a right-footed shot inside Butland’s near post to give the Hornets a two-goal cushion going into the break.

Unsurprisingly, the home side were quickly out of the blocks at the start of the second half and it took some smart defensive work by Cassetti to prevent Lovenkrands from getting a clear head on the end of a Burke cross.

The former Newcastle United man also had a shot block before a combination of Almunia and Nosworthy prevented him from getting on the end of a bouncing ball inside the six-yard box following more useful work by Burke.

After Watford had temporarily eased the pressure by forcing two corners, the Blues won two of their own, the second of which came after Almunia failed to deal with the initial set piece and some more last-gasp defending deflected another Lovenkrands strike behind.

The Hornets though, had been sloppy at times since the restart and they were fortunate not to be punished when the overlapping Paul Caddis was able to play in a low cross from the right which the stretching Thomas was inches away from connecting with.

Watford were also not too far away soon after when, following a short corner on the left, Abdi struck a curling cross-cum-shot narrowly wide of Butland’s far post. Clark then decided to make his first change on the hour, bringing on Nathan Redmond for Rob Hall.

In the 62nd minute though, came the latest example of the visitors’ sometimes supreme counter-attacking ability.

The Hornets found themselves with the freedom of the opposition right when a Blues attack broke down and Robinson was caught upfield. Vydra the led charge and slipped in Anya to his right after he had made up plenty of ground to get up in support. The right midfielder then squared the ball across the area to Deeney, who tucked away his second of the afternoon high into the roof of the net to make it 3-0.

Both sides made a change three minutes later as Adam Thompson came on for Pudil and Robinson’s tough afternoon was ended when he was replaced by Mitch Hancox.

Watford were soon back on the attack though, with Vydra firing over from the left side of the area after being found by Lloyd Doyley, who was now operating as left wing-back following the substitution.

The Blues weren’t too far away from a consolation in the 73rd minute when a Burke cross found Redmond in space at the far post and he headed down but the wrong side of Almunia’s right-hand upright. A limping Anya’s fine contribution then came to an enforced end when he had to make way for Sean Murray.

To their credit, the hosts were still refusing to lie down though, and Curtis Davies wasn’t too far away with a low shot after popping up in the Hornets area. Lovenkrands was closer still when an outstretched leg somewhat inadvertently connected with the ball on the edge of the six-yard box after nobody had been able to get a head on a Burke cross, but Almunia was able to get across and make the save.

Lovenkrands was booked for dissent after overly protesting when referee Craig Pawson refused to buy his appeals for a penalty after going down under Thompson’s strong challenge.

Vydra made way for Hogg with six minutes remaining and four minutes later they made it 4-0.

Battocchio nicked the ball away from Redmond in midfield and tried to play in Deeney but the ball ran to Abdi. His first shot was partially blocked and initially it looked like Battocchio would be able to round Butland and tuck the ball away. However, his follow-up was also blocked but only as far back as Abdi, who emphatically fired in his third goal in as many games from the edge of the area to round off another fine awayday.

Birmingham City: Butland; Caddis, Davies, Caldwell, Robinson (Hancox 65); Burke, Elliott, Gomis, Hall (Redmond 60); Thomas, Lovenkrands. Not used: Mullins, Morrison, Doyle, Spector and Reilly.

Watford: Almunia; Doyley, Nosworthy, Cassetti; Anya (Murray 73), Abdi, Chalobah, Battocchio, Pudil (Thompson 65); Deeney, Vydra (Hogg 84). Not used: Yeates, Bond, Geijo and Forestieri.

Bookings: Robinson for a foul on Abdi (18); Lovenkrands for dissent (78).

Attendance: 18,933 (2,454 away).

Referee: Craig Pawson.