Max Verstappen's manager has admitted the possibility that Honda could quit Formula 1 after 2020.
Next year is Verstappen's last chance to break the record as the youngest ever world champion.
And key to that chance, the Dutch driver's manager Raymond Vermeulen declared, is Red Bull's works engine supplier.
"We - that means Max, Jos and I - have been positively surprised by Honda," he told De Limburger newspaper.
"Don't forget how far they have come."
But the entire Verstappen camp is also expecting a shot at the championship in 2020 - or they could switch teams for the following season.
"The team must be ready from day one, including Honda," Vermeulen said.
"In Melbourne we have to be right there, because if you want to be champion, that has to be the case for 22 races.
"That was not the case this year, so there is still a step to take. You will not become world champion with ups and downs," he added.
Vermeulen said it clear that Verstappen, 22, is ready to win a title.
"Nothing can be improved with him now. He is a complete driver. The final push has to come from the team," he said.
"Helmut Marko has said it himself - it is up to them to give Max a car to become champion."
The warning is therefore clear: a change of teams could be on the cards for 2021.
"We are still in a fantastic situation with a top team, but we want to win," said Vermeulen.
Another complication is that Honda is currently not committing to Formula 1 beyond 2020.
"We are kept informed on the situation on a weekly basis. We have spoken ourselves with Honda in Japan," Vermeulen said.
"They say that 2020 is a very important year. They want to continue, but we are waiting for the white smoke."
"Nothing to worry about," said Vermeulen. "But before 2021, with the new regulations, it will be difficult to make the right choice. The past will be no guarantee of the future.
"We will see with our own eyes what Red Bull is doing and also listen carefully to what the others want."body check tags ::