Watford allegedly made a change in the dugout as a result of the club's poor performances in defence during the opening weeks of the season.
Javi Gracia had enjoyed a strong first full campaign at Vicarage Road, guiding the Hornets to the FA Cup final and coming close to finishing in seventh position in the Premier League table.
However, during the international break, Watford opted to replace Gracia with Quique Flores, who agreed to take on his second spell at the Hertfordshire-based side.
According to Sky Sports News, the club's hierarchy had been left unimpressed with the team's failure to defeat any of Brighton & Hove Albion, Everton, West Ham United or Newcastle United, while also shipping eight goals.
The report adds that the board were also disappointed that Ismaila Sarr and Danny Welbeck - two high-profile summer signings - had not been quickly integrated into the starting lineup.
Watford are next in action when they take on Arsenal on Sunday afternoon.