Brazil were dumped out of the World Cup by Belgium at the quarter-final stage, meaning Willian has already had more than three weeks off.
Brazil and Chelsea star Willian has been reported absent from training as rumours of a Real Madrid bid for the player continue to grow.
Manchester United, Real Madrid and Barcelona are chasing the winger.
Club officials knew he was returning late and now expect Willian back at Cobham on Wednesday.
The 29-year-old has been a primary target for the position this season, along with Internazionale's Ivan Perisic and Real Madrid's Gareth Bale, and Man United could be getting their man.
'[Leaving?] No, I'm back to England.
"I am very happy at Chelsea and I am very happy living in London", he is quoted by the Mirror as telling Globo Esporte.
But it is thought Willian may be trying to put pressure on Chelsea for a new contract, with his current £125,000-a-week deal due to run out in two years.