The latter is now at Real Madrid, and Ziyech is the one the Blues often turn to for creativity in the team.
The 27-year-old was in the lineup against Tottenham for the team's 0-0 draw at Stamford Bridge on Sunday.
It was not Ziyech's best game, but he has impressed so far this season since arriving from Ajax.
Asked by reporters about Hazard, the Moroccan international said: "Eden is a world-class player.
"You always take inspiration from that, how he plays the game.
"You always look at the small things, how he does stuff - and I can learn a lot from him."