The Morocco international is set to cost around £38million after a fee was agreed earlier this week.
But former West Ham goalkeeper Shaka Hislop believes Ziyech’s current Ajax team-mate Donny van de Beek would also be a top signing for Chelsea.
“These two lined up against each other in the Champions League earlier this season, so they would have seen each other first hand,” Hislop told ESPN FC.
“Given what we’ve seen from Ajax over the last couple of seasons, you take chances on almost any of Ajax’s players. This makes a whole lot of sense.
“It’s in keeping with everything you’ve seen from Chelsea and Frank Lampard – young, talented, a lot of upside to it. Yes.”