London - Andre Gray came off the bench to fire Watford into the FA Cup semi-finals with the late winner in their 2-1 victory over Crystal Palace on Saturday.

Javi Gracia's side took the lead through Etienne Capoue's first half strike before Michy Batshuayi equalised for Palace after the interval.

That was the signal for Gracia to turn to Gray, who maintained his reputation as Watford's super-sub by grabbing the goal that avenged the Hornets' 2016 FA Cup semi-final defeat against Palace.

The former Burnley striker has now scored the winner as a substitute three times in recent weeks, having also netted Watford's decisive goal against Everton and Leicester.

Gray's latest heroics moved Watford closer to finally returning to the FA Cup final 35 years after they lost to Everton in their only other appearance.

Watford had won both Premier League meetings with Palace this season and Gracia's team went close early on when Gerard Deulofeu's strike drew a good stop from Vicente Guaita.

Despite that save, Guaita looked nervous on a windy afternoon and the Spanish keeper made a hash of dealing with a Watford corner before Palace managed to clear. 

It was a mistake he repeated with fatal consequences as Watford took the lead in the 27th minute.

Flapping at a Jose Holebas corner, Guaita's weak punch failed to clear the danger and when the ball was diverted back to Capoue, the French midfielder slotted into the empty net from close-range.

Watford threatened a second goal when Deulofeu unleashed a rising shot moments later, but this time Guaita was up to the task.

Palace had laboured without Ivory Coast forward Wilfried Zaha, absent due to a calf strain, but they were more vibrant after the break and Heurelho Gomes had to keep out Max Meyer's diving header before Batshuayi fired just wide.

The visitors' pressure was rewarded in the 62nd minute when Gomes a risky pass to Adrian Mariappa.

Mariappa was far too slow to clear and on-loan Chelsea striker Batshuayi stole possession, advancing into the penalty area to drill a cool finish past Gomes.

It was the first goal Watford had conceded in this year's competition.

But Gracia responded by sending on Gray in the 77th minute and it proved an inspired move as he won it for Watford just two minutes after his introduction.

Roberto Pereyra was the catalyst with an incisive burst from midfield and the Argentine's perfectly-placed pass picked out Gray, who timed his run to poke a volley past Guaita from eight yards.

Aaron Wan-Bissaka should have forced extra-time when the ball fell to him after a Gomes mistake in stoppage-time, but the Palace defender blasted just wide.