Willian has agreed on a deal in principle to remain at Chelsea until the end of the domestic season, with his current contract having been due to expire on June 30.
Frank Lampard will be boosted by the news that the 31-year-old has agreed to stay until the domestic season is finished but it remains unclear whether he will compete in the club's Champions League campaign in August.
The outage of football across Europe due to the coronavirus pandemic has seen seasons extended beyond the typical cut-off date of June 30 for expiring contracts.