BT Sport's live coverage team knew better than to put any microphones near the West Ham dugout before this match. Hammers manager Slaven Bilic was seen venting his frustration on a pitch-side mic after his team conceded a late equaliser at home to West Bromwich Albion, and for long periods of this game he appeared just as vexed.

The Croatian was on his feet throughout, remonstrating with the officials over what he clearly saw as their failure to give a fair share of decisions in his favour. But when he reviews the DVD of this game, he will realise that his own team's final pass was just as much to blame for the dropping of two points.

A goal down to Troy Deeney's early penalty, they hit back to draw level when Andre Ayew came off the bench to equalise with his second goal for the club mid-way through the second half. But they could not find a second and were hanging on in injury time after Michail Antonio was sent off for a second bookable offence.

As worrying for Watford as their failure to build on their early goal will be the loss of former West Ham midfield player Mauro Zarate, signed from Fiorentina last month, who left the field on a stretcher late in the first half with what looked like a serious knee injury.

West Ham celebrate their equaliser at Vicarage Road (Getty)

To say that Watford made a fast start would be an understatement. West Ham were on the back foot in only the second minute, conceding a penalty when stand-in right back Cheikhou Kouyate challenged Zarate clumsily as the Argentinian ran onto Troy Deeney's pass from the left. It was a simple decision for referee Craig Pawson and Deeney drove the kick past Darren Randolph with a minimum of fuss.

There was almost a spectacular second for the home side when M'Baye Niang was allowed to run at the West Ham defence before unleashing a powerful shot from 25 yards that rose just over the crossbar.

But with Watford apparently in no mood to sit on their early lead, there were also chances for West Ham and Miguel Britos was at full stretch to volley away a dangerous cross from the left by Manuel Lanzini. Then Watford's Younes Kaboul – who had earlier made an adventurous surge up the right that included a flick over the head of an opponent – was forced to block a shot from Robert Snodgrass after Sofiane Feghouli had pilfered possession from Jose Holebas.

Mauro Zarate's injury will be a cause for concern for Watford fans (Getty)

Some of Watford's own challenges began to become a little desperate and Bilic made his frustration clear to fourth official Graham Scott. But even when referee Pawson produced a yellow card for daryl Janmaat's challenge on Michail Antonio, Snodgrass' free kick was neither cross nor shot – true of too many of West Ham's passes. And even when goalkeeper Heurelho Gomes could only palm Aaron Cresswell's low cross out to Snodgrass, the Scotland midfield player's first touch was heavy and the chance was gone.

Zarate was carried off in first-half stoppage time, twisting his knee as he tried to turn with no opponent involved, and Watford seemed badly affected by his absence, West Ham establishing second-half supremacy.

But Bilic was incandescent again when Kouyate fell as he battled Niang for possession but a free kick was awarded against the West Ham man rather than a penalty. And he was on his feet once more in disbelief as Antonio shaped to tap in Lanzini's diagonal low cross only for Gomes to get his hand to the ball first. And Gomes came to Watford's rescue a second time in as many minutes, leaping to his left to touch a header by Jose Fonte away for a corner. But even Gomes was helpless as Cresswell swung a fast, bouncing cross over from the left only for Antonio to nod the ball wide from two yards out.

Troy Deeney converted from the spot to hand Watford an early lead (Getty)

You felt a West Ham goal simply had to come and it duly did in the 74th minute. Antonio picked the ball up on the left and ran at Younes Kaboul before hitting a low, left-foot shot past Gomes. The ball hit the inside of the near post, then the far post and cannoned out, but only to the substitute, Ayew, who rolled it into the net.

Antonio then complicated things for his side when he handled the ball after a challenge and was shown a second yellow card. So instead of pressing for a winner, West Ham were left hanging on and Britos nearly made them pay but headed wide from a late corner kick. Fortunately for Watford, Holebas made no mistake with an equally important header at the other end, nodding away as Feghouli prepared to pounce on a deep cross.

Watford (4-4-1-1): Gomes; Janmaat (Cathcart 52), Kaboul, Britos, Holebas; Niang (Success 82), Cleverley, Behrami, Capoue; Zarate (Doucoure 45 + 6); Deeney

West Ham United (4-2-3-1): Randolph; Kouyate, Fonte, Reid, Cresswell; Obiang, Noble; Feghouli, Snodgrass (Ayew 65), Lanzini (Fernandes 90); Antonio