Zidane returned to Real on Monday just nine months after his abrupt departure, tasked with restoring the club to former glory after a hard season with Julen Lopetegui and Santiago Solari at the helm.
Hazard has made no secret of his ambition to work with the Frenchman, who he idolized while he was growing up. And the concern about the Belgian's future has crept into the training ground, with one Chelsea star declaring his worry.
Zidane was announced as the new manager at the Santiago Bernabeu on Monday evening, replacing Santiago Solari and returning - less than a year after he left the club.
Chelsea are reportedly set to demand £100 million from Real Madrid for star man Eden Hazard, amid growing fears of the Belgian's summer exit. I want in my team only players who want to play for Chelsea.
"He (Hazard) shows every day how important he is", Emerson told Sky Sports.
"Of course, Eden is a fantastic player, one of the best players in the world".
Willian said, "First of all, I hope he stays with us but in football you never know what can happen. Like Chelsea fans, we are afraid that he might leave, I still believe that he will stay and we really want him to stay".
Chelsea's confidence of keeping Hazard has been receding for months, with the Belgium worldwide having made no attempt to hide his attraction to Madrid while spurning Chelsea's attempts to reopen talks over a contract extension that would make him the highest-paid player in their history.
Having led the club to an unprecedented three successive UEFA Champions League titles during his first stint with the club, the 46-year-old tactician was identified as the flawless candidate to help get Los Blancos get out of their slump, with the club likely to finish the 2018/19 campaign without lifting a trophy.