Renault advisor Alain Prost has said that he's concerned the works team may struggle to beat rival teams running Renault power units next year.
As well as running its own race team, the French manufacturer also provides engines to Red Bull. A deal to supply Toro Rosso expired at the end of 2017, allowing McLaren to become a customer operation next season.
"The factory team will race against two well-established teams," Prost told Auto Motor und Sport this week.
"And both of those teams also have top drivers," the four-time world champion added. "Maybe even the best. On paper we cannot beat Red Bull and McLaren."
Renault sold its works team at the end of 2011 but continued to supply engines to Red Bull and Williams. It returned to Formula 1 as a team owner in 2016 after buying back the troubled Lotus F1 Team.
Since its return, it has been steadily rebuilding the depleted operations at Enstone. This year the team finished three places up, in sixth place in the constructors standings ahead of Toro Rosso, Haas and McLaren.
Prost insisted that Renault was in Formula 1 for the long-term and wouldn't be walking away from the sport again anytime soon.
"The entire organisation that Renault is still setting up already exists," commented Prost. "We will be here for a long time so it's important that we make progress every year.
"In the end, if we want to win, we will have to beat everyone," he said. "The comparison with the customer teams will help us to gain experience in order to get closer to the top teams.
"We will be better next year," he pledged. "For me, the pressure is positive, even if it is difficult."
Next year, Renault's operations will be boosted by the signing of Marcin Budkowski, the FIA's former F1 technical chief.
The squad had agreed a delay to the start of Budkowski's appointment to April 2018. That's because other teams fear he will provide Renault with confidential information as a result of his former position with the governing body.