Roman Abramovich and Jose Mourinho are set to collide as the Portuguese continues to leave out Juan Mata, reports the Sunday People.
Mourinho, who returned to Chelsea for a second managerial stint this summer, has so far refused to play to Spanish trio Mata, Fernando Torres and Cesar Azpilicueta.
The three, who remain close friends, are reported to be growingly unhappy as they feel Mourinho isn't giving them a fair chance to prove themselves.
The omission of Mata is particularly strange as the Spanish playmaker has been Chelsea's Player of the Year in both of the seasons he has had with the club.
Mourinho could now be set to clash with the Chelsea owner Abramovich as Mata and Torres remain firm favourites of the Russian oligarch.
The Sunday People is reporting that Abramovich showed unity and support to the pair whilst visiting the dressing room after the 2-1 defeat to FC Basel of Wednesday night last week.
All three players were preferred by Rafa Benitez but Mourinho has since decided to head in another direction.
The Chelsea boss is happy to let Mata swap Stamford Bridge for Atletico Madrid in January if it brings Oliver Torres to west London in exchange.
But, along with many Chelsea fans, Abramovich disagrees with the decision to leave out Mata and is not willing to see the player sold.
After being asked about Mata by Jamie Redknapp on Sky Sports, Mourinho snapped: “I understand that lots of people including yourself, you like very much Mata and you believe he should be in that position.
"I think that the evolution of the team, and the way I want to play with Mata and Oscar together – I want that. But Juan has to work and adapt to a certain way of play because I am not ready to change Oscar’s position.”