Renault only needs "patience" and it can eventually catch the top teams in Formula 1.

That is the view of Frenchman Eric Boullier, the former McLaren boss who actually entered F1 to front a former incarnation of the team based at Enstone.

"It's a big challenge to take over a team and reconfigure it," he told Ouest France newspaper when asked about Renault's difficult 2019 season.

"If Daniel Ricciardo decided to come, there are positive signs. But you do not build a team overnight.

"It's easy to see what does not work, but years of investment - and years of recruitment in a difficult social context - are required to catch up."

Boullier believes recruiting top people is one of Renault's biggest challenges.

"F1 tends to protect its key people," said the Frenchman, who is now involved with the organisers of the French GP at Paul Ricard.

"So recovering in that area can take several years. You just have to keep pushing the elements until the day it works."

Boullier says that besides the signing of Ricciardo last year, there are several other positive signs at Renault.

"They are now at the level of the best engines," he said.

"The chassis is not quite there but we can see they are continuing to restructure. It's a positive sign - they're almost there. They just need a little patience."

Along with Williams, Renault is the only team to make a driver change for 2020, with Esteban Ocon arriving to replace German Nico Hulkenberg.

"I've known him since he was 12, so I don't worry for him," Boullier said when asked about Ocon.

"The main difficulty for him is to be a French driver in a French team - it's a long time since we've seen that. He will have to manage his agenda and his schedule because he will be in great demand.

"But for the rest, he has his talent and also his experience," he added.