Summer signing Ashley Fletcher capped his debut with a late winner as Watford edged out Premier League rivals Crystal Palace 1-0 to reach the third round of the Carabao Cup.

The tie increasingly looked like it would need to be decided by a penalty shoot-out until four minutes from the end of normal time when Cucho Hernandez curled a fine cross to the far post and the former Middlesbrough striker converted to send the Hornets through.

Watford struggled as an attacking force in the first half, struggling to gain enough of an attacking platform in midfield to build any pressure from the final third.

Their most promising moments came on the counter but these foundered due to a lack of cohesion or the quality of the final ball.

William Troost-Ekong was fortunate that a defensive lapse did not result in Jean-Philippe Mateta making the breakthrough, but soon after the Nigerian did extremely well to prevent the Frenchman from heading the visitors in front.

Following the introduction of Emmannuel Dennis at half-time, the hosts were to offer a greater threat after Troost-Ekong had been superbly denied by Jack Butland.

Substitute Christian Benteke and Cheikhou Kouyate both had good opportunities for the visitors, but with the game increasingly destined to be decided by penalties Watford made the decisive breakthrough.

Xisco Munoz, as expected, shuffled his pack for the tie but four players – Troost-Ekong, Imran Louza, Peter Etebo and Ken Sema – did keep their places from the side that started Saturday’s defeat at Brighton & Hove Albion.

Fletcher became the latest player to make his Hornets debuts, there was a first start for permanent summer addition and former loanee Danny Rose, Francisco Sierralta was back at the heart of the defence while Kiko Femenia was fit to be included among the replacements.

Crystal Palace went even stronger in terms of what could be considered their first choice XI, with seven players keeping their place after starting Saturday’s 0-0 draw against Brentford.

The four changes saw keeper Butland, James Tomkins, Jeffrey Schlupp and Mateta come into the side.

Watford Observer:

Peter Etebo challenges Jean-Philippe Mateta

The Hornets started positively, playing at a good tempo and keeping the ball well in the opening exchanges.

Palace has the first opportunity to pose a threat on goal when Rose fouled Conor Gallagher close to the right touchline, but the hosts headed clear the free-kick and dealt well enough with the resultant phases.

The Hornets threatened when Rose found Hernandez on the left and the Colombian slipped a lovely pass into space for the former Tottenham Hotspur man to cross but he was unable to pick out Fletcher or Joshua King.

Troost-Ekong was fortunate when his pocket was picked by Mateta close to the byline, the Eagles winger immediately closing into the area before shooting from a tight angle, forcing Ben Foster to save with his legs.

Palace went even closer in the 17th minute when Jordan Ayew found Gallagher in space on the left side of the box, he stood up a cross which Mateta looked odds-on to head in from close range but Troost-Ekong did very well to get in the way and deflect the effort over the bar.

Watford Observer:

The moment when Mateta was denied by William Troost-Ekong

Watford dealt with the corner and immediately broke away, Hernandez trying to slide a pass through to King in the area but the ball was intercepted.

There was some concerning moments for the hosts in the 22nd minute when Peter Etebo did well to dispossess Mateta but after taking a few strides the midfielder kicked the ball into touch and went down holding his right knee. The situation didn’t look promising but after receiving treatment the Stoke City loanee was able to continue.

A driving run from Sema then saw him work the ball to Fletcher, his cross from the right was headed clear to the edge of the 18-year-box where Louza struck a left-footed effort over the top.

Palace were continuing to look more threatening though, and in the 35th minute they were almost in again when Wilfried Zaha found Schlupp in space on the left side of the area, he crossed and Mateta’s goal-bound was pushed over by the stretching Foster.

This led to a passage of two corners, the second of which saw Tomkins flash a header wide of the left-hand upright.

Munoz chose to make a change at the start of the second half, bringing on Dennis for King, but within the opening 90 seconds of the second period the Hornets were almost undone when Gallagher slid a free-kick down the side of the area to Zaha. He opened up what looked a good shooting opportunity on his left foot but instead chose to play the ball across the six-yard box with his right and the hosts were able to scramble it away.

That was an escape but within four minutes the Hornets almost made the breakthrough when Louza clipped in a free-kick from the right side of the area, picking out the unmarked Troost-Ekong whose header was superbly tipped over by Butland from barely eight yards out.

This gave the Hornets renewed heart and soon after Dennis was released on the counter, he burst clear, only to have his shirt pulled by Gallagher. Referee Tim Robinson played the advantage though, enabling the striker to find Hernandez in space on the right, but the Colombian tried an ambitious first-time effort that went high and wide. Before play restarted, Gallagher was cautioned for his shirt pull.

Watford Observer:

Ben Foster is all smiles

Watford were looking much more energised and soon after more promising build-up play ended with Fletcher seeing an attempted cross from the right blocked.

Gallagher was in danger of walking of tight rope when he pulled back Dennis soon after but Robinson did not deem the offence worthy of even a conversation. Instead, it was to be Sierralta who was to receive the game’s next yellow card for a foul on Schulpp.

Femenia made his first appearance of the season as a 62nd-minute replacement for Jeremy Ngakia. Soon after Patrick Vieira made a double change as Benteke and James McArthur came on for Mateta and Gallagher.

Those changes saw Palace establish a firmer foothold again though, and in the 74th minute Foster had to get smartly down at his near post to keep out an angled strike from Benteke.

The visitors had another opportunity from a corner soon after when the ball sat up invitingly for Kouyate eight yards out, but he swivelled and struck his attempted finish over the top.

Tom Cleverley replaced Sema in the 76th minute as the possibility of a penalty shoot-out started to loom a little larger in the minds of those inside Vicarage Road.

Tyrick Mitchell came on for Tomkins with nine minutes of normal time remaining as Vieira made the last of his changes.

Schlupp fired harmlessly wide of Foster’s right-hand pass but with four minutes of normal time the prospect of penalties was seemingly averted as the Hornets made the breakthrough.

Watford Observer:

The goal scorer celebrates with Cucho Hernandez

Rose made sure he got to the ball ahead of Ayew on the left and played a nice pass down the side to Hernandez. He teased Joel Ward before curling a lovely cross to the back post where Fletcher gambled and was rewarded as he slid in the opening goal of the night.

Four minutes of injury time afforded Palace hope of salvaging an equaliser but the likes of Hernandez and Sierralta put their bodies on the line to ensure the Hornets held firm.

Watford: Foster; Ngakia (Femenia 62), Troost-Ekong, Sierralta, Rose; Louza, Etebo, Sema (Cleverley 76); Hernandez, Fletcher, King (Dennis 46). Subs not used: Elliot, Cathcart, Baah, Alvarado.

Crystal Palace: Butland; Tomkins (Mitchell 81), Guehi, Andersen, Ward; Gallagher (McArthur 63), Kouyate, Schlupp; Ayew, Mateta (Benteke 63), Zaha. Subs not used: Guaita, Kelly, Ridewald, Rak-Sakyi.

Bookings: Hernandez for a foul on Zaha (43); Gallagher for pulling back Dennis (54); Sierralta for a foul on Schlupp (60); Rose for time wasting (90).

Attendance: 9,011.

Referee: Tim Robinson.