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.
FIFA had issued guidance that players and clubs should attempt to end the season with their current squads but made it clear that both parties had to agree to continue working together.
Indeed, Chelsea are still tying up Pedro's agreement to carry on for another month or so amid an agreement being put in place for him to move to Roma next season.
Pedro's deal is complicated by the fact that he has a pre-contract in place ahead of a free transfer. Willian, however, has yet to agree terms with any club for 2020-21.
Chelsea still have time to agree on a longer-term deal with Willian, who has asked for a three-year contract, but the Blues are currently only willing to sign him on a short-term basis.
Arsenal and Tottenham are thought to be two clubs interested in the Brazilian, who has grown comfortable in London due to his family situation in the English capital.
Meanwhile, Chelsea have avoided the same problems that they have had with Willian and Pedro for both Olivier Giroud and Willy Caballero by activating one-year extension clauses in their contracts.
Lampard had spoken of the importance of keeping his squad together for the final weeks of the season as he competes for a top-four spot and Champions League football next term.
"We want them to extend their stay and make sure they can see out the season," Lampard told reporters via a Zoom conference call ahead of their 2-1 win over Aston Villa.
"I see both sides. I see the individual player because I was one, and I respect that they have both been great servants to the club.
"I’ve had nothing but open conversations with them. We’re just trying to make that extension happen. The players have to be happy. We have to be happy. Hopefully we can get there before the 23rd of June, next week, because that’s the day we have to get it done by.
"Anyone around us knows that. So we'll keep talking and hopefully they stay on."
Willian will also play in the FA Cup, which sees his side face Leicester City in the quarter-final on Sunday, while the final could potentially be his last game for the club on August 1 should the Blues get there.
Chelsea's eight loanees in the Championship have mostly agreed to continue on with their respective clubs, while the club has sold Mario Pasalic to Atalanta in a deal worth around £13 million ($16m).