Max Verstappen admits he is already worried about Red Bull's prospects in 2018, after Renault said a "big" engine upgrade would not arrive until next year.
Despite recent improvements to the team's RB13 and a run of three consecutive podium finishes, Red Bull still trail Mercedes and Ferrari on pace with their pre-season championship aspirations already appearing forlorn.
After seven races, the former world champions are over 100 points off the pace in the Constructors' Championship, while Verstappen is nearly the same adrift of drivers' points leader Sebastian Vettel.
Red Bull had been hoping for a sizeable Renault engine update but Cyril Abiteboul, the French manufacturer's F1 chief, said in an interview that, while small improvements are being made every race, there was "no magic bullet" and that "frankly the next big upgrade will be next year".
"Then we will have a completely new concept," Abiteboul told F1's official website. "That will make a difference - but as I said 2018."
But that timetable has left Verstappen, who retired from Sunday's Canadian GP with an engine problem when running in second place, concerned for the future.
"I want to win and I think the team can win," Verstappen told a TV show in the Netherlands, Peptalk, on Monday after the Montreal race.
"The car is a little better but there's no new [engine] model this year as you'd have read. They promised this, but in the end little has arrived in terms of updates [in 2017].
"That's very disappointing. I'm concerned about next year. This year we wanted to go for the title but we're far away from that."
Speaking to Sky F1 at the Canadian GP, Red Bull chief Christian Horner said "hopefully there's a bit more performance" at the next race in Baku when the team are scheduled to install the third engines of the season on their two cars.
But asked about the prospect of any significant update arriving, Abiteboul claimed in his interview "it was Red Bull who said that there would be an upgrade", rather than the French manufacturer themselves.
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