Chelsea boss Frank Lampard has spoken of his "love" for Willian, but he said it falls on the club to decide whether to hand him a new contract.
Willian is in the final year of his deal at Stamford Bridge and will be free to negotiate with foreign clubs in January.
Per Goal's Nizaar Kinsella, Lampard said of Willian's contract: "The word isn't 'no-brainer' because I can't get involved in the money. That's up to the club to do. But everyone sees how much I'm relying on him, and picking him and in what he is producing, I love him at this football club. So there's my answer."
The manager added that he wants "to see him happy" and that his former team-mate has been a "joy" to work with.
Lampard also said he "saw him being huge in the way I wanted to play" when he took over as head coach in the summer, not only for his ability to beat defenders before getting a cross into the box or a shot on goal, but also "his off-the-ball work [which] is an outstanding example for Callum Hudson-Odoi, for Christian Pulisic."
He added the 31-year-old does the defensive side of the game "brilliantly with absolute humility."
Lampard gave Willian, who made his 300th appearance for the club in October, the captain's armband in Saturday's 2-0 win over Crystal Palace as Cesar Azpilicueta was on the bench.
Willian helped Tammy Abraham open the scoring with a lovely assist:
Chelsea author Mark Worrall and The Athletic's Liam Twomey were impressed with his performance:
The winger has now contributed three assists and two goals in Chelsea's last six Premier League appearances.
In Pulisic (21) and Hudson-Odoi (19), the future of Chelsea's flanks is secure, but with Pedro also in the final year of his contract at Stamford Bridge, it might not be wise for the Blues to let both of their more experienced wingers leave next summer.
Of the two, Willian is the more obvious choice to retain. Pedro is a year older, so he'll be 33 next summer, and he hasn't been used as much by Lampard.
The Brazilian has played 1,088 minutes of football this season, while the Spaniard has been on the pitch for 529 minutes, less than half that time.
Pulisic and Hudson-Odoi can continue to learn from Willian for another year if he's given a new contract, by which time they'll be more ready to stand on their own.