Watford have confirmed the exit of Quique Sanchez Flores, who will leave at the end of the season.
Flores joined the club in June and guided them to safety in the EPL.
It is believed that former Napoli coach Mazzarri will be his replacement.
A statement from Watford read: “We would like to thank Quique. He and the team achieved the target set them at the start of the season of staying in the Premier League for a second year.
“Quique leaves with all our best wishes for the future and the knowledge he is always welcome at Vicarage Road.”
Flores also guided Watford to the FA Cup semi-finals this season, losing 2-1 to Crystal Palace at Wembley, but speculation mounted about his future following their poor end to the league campaign.
Watford currently sit 13th in the table with a game to go but a run of just four league wins in 2016 has meant a promising start to the season has fizzled out.