Chelsea chiefs are working on securing Willian to a new contract.
The Brazilian wide-man, 31, is out of contract in June and wants to stay at Stamford Bridge.
However, the veteran wants a three-year package, while Chelsea famously are reluctant to offer more than a 12-month extension to players in their thirties.
But both Willian and the Blues are keen to get the situation resolved before the end of the season.
That's even though the arrival of Ziyech will put the South American's position under threat.