Vladimir Ivic said after being named manager of relegated Watford he needs to adapt as fast as possible to English football if he is to take them straight back to the Premier League.
The 43-year-old Serbian signed a one-year contract - with the option of extending it by a further year - and replaces Nigel Pearson.
Pearson was controversially sacked last month with two matches remaining of the Premier League season, and Hayden Mullins failed to keep them up as caretaker manager.
It ended a five-year stay in the top tier for the 2019 FA Cup finalists.
Ivic - who coached PAOK to the 2017 Greek Cup and guided Maccabi Tel Aviv to successive Israeli league titles the past two seasons - is Watford's fourth full-time manager in less than a year.
"First of all, from the beginning I have a big expectation of myself and of my coaching staff," Ivic told watfordfc.com.
"It's my first time in England and I need to adapt as fast as possible, to do the best for the club is very important to me."
The former Serbia international midfielder will start work with Watford on Monday, alongside his three-strong coaching team.
"I've worked with my coaching staff for three years, so I know that we will ask the most from ourselves so we can help the players to achieve the club's goals," said Ivic.
The Championship season is due to get underway on the weekend of 12 September.