Willian was dropped for Chelsea's 2-2 draw with Leicester last weekend because of his attitude, according to reports.
The 31-year-old started the game on the bench before being given the nod at the King Power Stadium in the second half on Saturday.
The Brazilian winger was said to be sulking during training after he saw a January move to Barcelona to fall through, prompting Blues boss Frank Lampard to take action, according to The Sun.
Lampard instead went with Pedro for the Premier League clash against the Foxes before sending on Willian in place of the Spaniard in the 74th minute.
The Brazil international had been linked with a late January move to Barcelona but the Catalan giants pulled out of the deal and will instead snap him up on a free this summer.
Willian, who is a free agent in June when his current contract expires, felt aggrieved by how the transfer window played out which left Lampard with no choice but to drop the veteran forward.
With his current deal nearly up, Willian is free to meet with other clubs and has reportedly has met with Barcelona representatives on two occasions over a move to the Nou Camp.
Barcelona's bid to sign Willian has been eased by the fact the winger's representative agency, Sport Invest, is the same as Coutinho, who joined the club two years ago.
Barca's interest in the former Shakhtar Donetsk man goes back two years, when he came close to joining the club before opting to remain at Chelsea.
The Spanish club were interested in signing him for a fee in January but Chelsea weren't willing to let him go given their current lack of options in the final third.
As a result, they now look set to lose one of their most experienced players for nothing in July, unless they can somehow convince him to stay.
If he does leave, Willian will bring the curtain down on a successful six-and-a-half year stay at Stamford Bridge, that has yielded two Premier League titles, one FA Cup and one League Cup.