Watford, who sacked Marco Silva last week after a dramatic downturn in results, eased past Bristol City in round three despite making several changes to their starting XI.
Gracia, however, is likely to name a strong side as he looks to get his Hornets tenure off to a winning start. The Spaniard prefers to set his side up in a 4-4-2 or 4-3-3 formation and it'll be intriguing to see if he continues that trend at Watford.
Our unique algorithm has predicted the Hornets side it believes will start the game.
Football Whispers uses data to predict teams’ starting XIs, taking into account injuries, suspensions, the statistical likelihood of a player being selected, the competition the match is in, players’ previous performances and the opponent’s style.
And you can also give it a go yourself. Just click ‘create your own’ on the line-up at the top of the page and pick your ideal XI for the game.You can also see each player’s stats once you’ve selected them.
When you’re happy with your team, press confirm and you’ll be able to share it with your friends via social media.