Fiorentina are due to tackle West Ham in the Europa Conference League final in Prague on Wednesday evening.
David Moyes’ side struggled in the Premier League this season, but have the chance to end the season on a high with a piece of silverware.
Zarate has played for both West Ham and Fiorentina, and believes La Viola must pay extra attention to Hammers hitman Antonio.
“West Ham have Antonio in attack and despite the arrival of new forwards he always manages to play”, Zarate told Italian radio station Radio Bruno.
“An animal, a very dangerous player.”
Zarate is expecting a real spectacle in Prague, especially as he feels the West Ham fans will make sure the atmosphere is superb.
“I expect a great final, even if the English have not done well in the league compared to the squad they have.
“Away the Hammers fans are fantastic, it almost feels like playing at home.”
Fiorentina finished eighth in the Serie A standings this season.