Red Bull chiefs were having more meetings with their Ferrari counterparts on Saturday.
The talks at Suzuka are amid the very real threat that the energy drink company could pull both of its teams - Red Bull and Toro Rosso - out of the sport after November’s Abu Dhabi grand prix.
With Mercedes now out of the question, Red Bull is demanding that it must now conclude a deal with the other competitive engine supplier for a full ’A’ spec of Ferrari’s power unit.
One of those in Saturday’s Ferrari meetings was the Red Bull official Dr Helmut Marko, who told Germany’s Sport Bild: "We are waiting for a proper piece of paper on which we are offered a competitive engine for 2016.
"Otherwise, formula one loses four cars."
Perhaps to sweeten the deal, Red Bull has hinted that as the Ferrari works team tries to chase down Mercedes for the title, it may be able to help in Japan.
"If Vettel is on top again and Mercedes is again weaker, we could get between the Ferrari and the Mercedes and save Sebastian (Vettel) a few points in his fightback," said Marko.
But if Red Bull does quit, the sport stands to lose exciting names like Daniel Ricciardo and the teen sensation Max Verstappen.
The latter Dutchman, however, is now regarded as perhaps the hottest property in F1, and so if he is without a drive, other teams will presumably try to snap him up.
Max’s father Jos told the Dutch newspaper De Telegraaf: "Max will be in formula one next season. 100 per cent."