According to Neil Fissler of the Sunday Express, the 29-year-old is considering his options in the midseason market, especially with the Blues linked with a swoop for Paris Saint-Germain forward Lucas Moura.
"A move for Moura would make Willian surplus to requirements, and they know they will won't have any problems in finding a buyer," Fissler said. "The Blues' first preference would be selling him to a Chinese Super League club who have been interested in him for well over a year."
Mourinho is said to be a "big Willian fan," and having worked together previously at Stamford Bridge, the Portuguese knows how to get the best from the forward. United are reported to be on the hunt for another option in the final third, having missed out on Inter Milan star Ivan Perisic in the summer.
As Samuel Luckhurst of the Manchester Evening News noted ahead of the recent meeting between the two teams, it appears the bond remains strong between the player and his former coach:
Samuel Luckhurst @samuelluckhurst
Willian waits for Mourinho to finish chatting with a Chelsea member of staff. Gets a hug and a kiss from the United manager. #mufc2017-11-5 16:01:22
Willian has fallen down the pecking order at Chelsea since manager Antonio Conte's arrival in 2016, with Pedro and Eden Hazard preferred in support of a striker.
As a result, Willian's form has suffered when he has been on the pitch. At times, his decision-making has been rusty and his shooting wild. Understandably, he hasn't appeared to be in sync with his team-mates. At this point in his career, he'll want to be playing regular football.
Under Mourinho at United, he could get that. However, after allowing Nemanja Matic to move to Old Trafford in the summer and seeing him flourish thereafter, there will surely be some hesitation on the Blues' part to allow Willian to follow the same path.
Blues In for Bernard
Chelsea are reportedly one of a trio of Premier League sides exploring the possibility of signing Shakhtar Donetsk winger Bernard.
According to UOL (h/t the Sunday Mirror), the Blues, Arsenal and Liverpool are all in for the Brazilian, who will be available on a free transfer in the summer if he fails to sign new terms with the Ukrainian side.
It's reported Shakhtar would rather cash in during the January transfer window and have thus placed an £11.5 million valuation on the 25-year-old.
Bernard has long been one of the most exciting attackers in the Shakhtar side, though with his contract close to expiring, he appears to be on the cusp of a new challenge. As The Independent's Jack Pitt-Brooke noted earlier in the season, he shone against Manchester City in the UEFA Champions League:
Jack Pitt-Brooke @JackPittBrooke
Shakhtar are good. They're keeping the ball well and creating good chances. Especially impressed with Bernard, Taison and Fred.2017-9-26 19:02:15
The talent has always been there with Bernard, and after years of struggling to live up to the billing he received as a youngster, he's beginning to realise his potential.
It would be no surprise to see a Premier League side take a punt on him given his contract situation, whether that be in January or at the end of the season. But unless Willian does leave in January, it's tough to see where Bernard fits into the Chelsea squad.