Watford starting XI: Foster; Femenia, Troost-Ekong, Cathcart, Masina, Rose; Sissoko, Kucka; Sarr, Dennis, Hernandez.
Watford substitutes: Bachmann, Ngakia, Louza, Cleverley, Joao Pedro, Sema, Gosling, Fletcher, Tufan.
Liverpool starting XI: Kelleher; Alexander-Arnold, Matip, Van Dijk, Robertson; Henderson, Milner, Keita; Mane, Salah, Firmino.
Liverpool substitutes: Adrian, Konate, Gomez, Oxlade-Chamberlain, Minamino, Jota, Tsimikas, Origi, Williams.
New Watford boss Claudio Ranieri appears to have gone with a 5-2-3 or 3-4-3 system in his first game at the club.
Ben Foster starts in goal with William Troost-Ekong, Craig Cathcart and Adam Masina as the centre backs.
Kiko Femenia and Danny Rose will be the wing backs, flanking Moussa Sissoko and Juraj Kucka in midfield.
Ismaila Sarr and Emmanuel Dennis will then play on the flanks, supporting Cucho Hernandez in attack.
Joao Pedro is named on the bench, joining Daniel Bachmann, Jeremy Ngakia, Imran Louza, Tom Cleverley, Ken Sema, Dan Gosling, Ashley. Fletcher and Ozan Tufan.
Meanwhile, Liverpool are forced to go with Caoimhin Kelleher in goal with Alisson unavailable.
Trent Alexander-Arnold returns at right back, joining Joel Matip, Virgil van Dijk and Andrew Robertson in defence.
James Milner moves into midfield, joining Jordan Henderson and Naby Keita.
Roberto Firmino leads the attack in place of Diogo Jota, with Mohamed Salah and Sadio Mane on the flanks.
Jota is named on the bench, joining Adrian, Ibrahima Konate, Joe Gomez, Oxlade-Chamberlain, Takumi Minamino, Kostas Tsimikas, Divock Origi and Neco Williams.