Canada - Max Verstappen says he is worried Red Bull's performance.
A concerned Verstappen
The young Dutchman is already under contract for next year, but after retiring in Montreal he insisted 2017 has been "completely crap" so far.
Team boss Christian Horner excused the 19-year-old, though.
Horner said: "He knows how hard the team is pushing to make the car better. He'll see the big picture.
"We were racing against a Mercedes (in Canada) and we beat Ferrari. Max hasn't had the result but it's still a long season. His time will come."
But Verstappen said his concerns are not just about 2017, particularly following the latest news from engine partner Renault.
He told the Dutch broadcaster Ziggo Sport Totaal: "We wanted to go for the world title this year, but we are far from it,"
Verstappen's ambition
Renault has now said the power unit will not be significantly updated for the rest of the year, and Verstappen admitted: "I'm worried, also for the direction for next year.
"I want to win and I absolutely think this team can. You can see we have improved the car a lot. But the power is yet to come.
"And right now, as you may have read, there will be nothing more (in 2017). Updates were promised but there have been few."