Fernando Alonso and McLaren insist Renault's recent reliability issues are not a concern for 2018.
McLaren will switch from Honda power to Renault next year in a move the team hopes will result in a return to podiums and victories. Renault engines have won races in with Red Bull this year, but at recent rounds have also suffered a significant amount of reliability issues.
Toro Rosso has suffered the most with problems in recent races, but all six Renault supplied cars have exceeded their power unit quotas on multiple occasions this year.
Asked if the problems are a concern ahead of 2018, especially as drivers will be limited to three power units per season rather than four next year, Alonso said: "No, not really.
"Renault is definitely one of the best engines out there and in the last 10 or 12 years it has been the most successful engine company in F1.
"So I have zero doubts [about 2018]."
McLaren sporting director Eric Boullier pointed out that the majority of the recent issues have occurred on the Toro Rosso, which is due to switch to Honda next year.
"It's mainly affecting one team," he said. "There are no worries [about 2018]. They [Renault] are not on top of their game in the same way Mercedes is, but I think they have sorted out most of the issues.
"There's big step to make, but they know that."
The next round in Abu Dhabi will be McLaren's last race with Honda power after going three seasons without scoring a podium.