Former Watford club doctor Richard Collinge is attempting to sue the club under grounds of discrimination.
Collinge's accusations of discrimination are based on his nationality.
Collinge was dismissed by the Hornets in September 2016, less than two years into his second spell with the club.
He was replaced by Italian Giorgio Gasperini whilst his compatriot, Walter Mazzari, was manager of the club.
Watford are denying the allegations and will argue that the decision to dismiss Collinge came as a result of them wanting to hire a permanent club doctor as part of a restructure.
Collinge's first stint at Watford took place from 2002 and 2011 and he has also made spells with the likes of Wigan, Montreal Impact and Cardiff City.