Matt Le Blanc will reportedly walk away from 'Top Gear' unless Chris Evans is replaced.
The former 'Friends' star joined the programme's presenting team alongside Chris earlier this year, but the new-look show has been undermined by rumours of infighting, with Matt said to be frustrated by the flame-haired presenter's on-set attitude.
A source said: "The big question now is who goes and who stays.
"The team does not gel at all, and the atmosphere between the presenters is decidedly frosty. It's very much a picture of him - Chris - and them.
"Matt has already indicated that he won't continue on any further series if Chris remains a part of it. And he is far from the only one who isn't happy."
Chris is said to have become frustrated by the other members of the 'Top Gear' team, which also includes Rory Reid, Sabine Schmitz, Chris Harris and Eddie Jordan.
A source told The Sun on Sunday newspaper: "Chris is not encouraging when any of the others are doing their links.
"On one occasion this month he even pretended to bump his head against a wall in frustration when Eddie Jordan kept fluffing his lines.
"He also seems to be jealous of the attention and praise which has been heaped on Chris Harris and Rory Reid in particular since the show began.
"You would have thought that with his experience, he would help out those new to studio recording. But he doesn't encourage them in any way.
"He just isn't interested. He doesn't even hang out with the others back stage and firmly keeps his distance from all of them at the aerodrome."
A BBC spokesman and spokesman for Chris has declined to comment on the report, while a spokeswoman for Matt said: "Nothing has been discussed or decided."