During a disastrous 2015-16 season where the Blues finished 10th in the Premier League, Willian was the only Chelsea player to emerge with his reputation enhanced. The Brazil international was rewarded with a new four-year contract in July and this season he has shared duties in attack with Pedro as part of Antonio Conte's refined 3-4-3 formation.
While Chelsea march towards a fifth Premier League title, things could have been very different for Willian. His former manager Mourinho spent close to £150m in strengthening his United squad during the summer transfer window, with four players in Eric Bailly, Zlatan Ibrahimovic, Henrikh Mkhitaryan and Paul Pogba arriving at the club, Willian was at the time also reported to be part of those plans.
When asked if he had offers to leave Stamford Bridge last summer, Willian told Globo Esporte: "From Manchester United, because Mourinho is there too. From other clubs I do not know, but there are always some things on the internet. But I am glad to hear than there are clubs that admire my work.
Over the last 13 months, two of Willian's teammates for club and country have left the Premier League to join the Chinese Super League. Following Ramires' move to Jiangsu Suning last January, Oscar also departed for the Far East at the start of 2017, joining Shanghai SIPG for a reported fee of £60m.
While Oscar in particular has received criticism for leaving one of Europe's major leagues at just 25, Willian says he can understand the decision and does not rule out eventually making the move himself, although he insists it would be a difficult decision having fallen in love with London.
"It is a very personal decision, it belongs to every player," Willian said. "A lot of people judge the players that go there, but only us, players, we know how this soccer life is difficult, fleeting and very fast. So in making this decision, we end up thinking about our future, our children and family.
"I do not know if I would go or not. What I can say is that I am happy at Chelsea. I feel very good there, like it is my home."
He continued: "I have affection for everyone there, I am well adapted to the city, my family loves to live in London. It's a difficult change, so it would have to be a though-out decision made with my family."