Marek Hamsik has described Maurizio Sarri as a "sick man" whose obsession with football has improved the Napoli captain the most.
Sarri departed the Stadio San Paolo at the end of last season after Napoli narrowly missed out on dethroning Juventus in Serie A.
Napoli finished four points behind Juve in their quest to win a first Scudetto since 1990, and Sarri gave way to Carlo Ancelotti before taking over at Chelsea.
Hamsik, who joined Napoli in 2007, is comfortable with the transition to Ancelotti, but credits Sarri with a significant influence on his career.