Fernando Alonso has issued a 'Honda or me' ultimatum to McLaren, according to Germany's authoritative Auto Motor und Sport.
It appears that the fiery Spaniard's three years of patience are finally up, amid rumours he faked a Honda engine failure to retire from last Sunday's race at Spa.
"He had a funny feeling with the car," said team boss Eric Boullier, defending Alonso.
Yet Honda's Yusuke Hasegawa said: "We could not find anything wrong in the data."
The report explains that if McLaren dump Honda, it would be a simple breach of contract but with no consequences.
However, if McLaren nudges Honda into quitting the deal, that would involve millions in compensation for the British team.
"In what world do they live?" Red Bull's Dr Helmut Marko asked. "If you get rid of someone, you don't also get money."
So at the moment it appears to be a situation of stalemate, with McLaren waiting for Honda to make a decision, and vice versa.
Alonso is now making clear what he thinks should happen, particularly as his best alternative for 2018 appears to be a move to Williams-Mercedes.
Boullier said: "With a Mercedes engine, we would be two seconds faster than Williams."
"There has to be a change," Alonso is quoted as saying by Spain's El Mundo Deportivo.
"I think there are answers out there but we have to find them - and they won't come from looking at the sky.
"We have to sit down and work and hope to find the best solution for next year."
Alonso has picked up 10 points so far in 2017.
