Alain Prost says Renault Formula 1 officials were a bit surprised when Daniel Ricciardo agreed to join the team for the 2019 season, but stresses the Australian is aware of the challenge he faces in trying to take the team back to the front of the grid.

Ricciardo announced at the beginning of August he would be quitting Red Bull at the end of the season in order to join Renault on a two-year deal, partnering Nico Hulkenberg from 2019.

The move came as a surprise to most of the paddock given Renault's relative level of competitiveness compared to Red Bull - the team has not scored a finish higher than fifth since its works return to F1 in 2016 - as well as to team advisor and four-time world champion Prost.

Speaking on F1's Beyond the Grid podcast, Prost said that 2019 was too early to expect Renault to be fighting at the front of the order with Mercedes, Ferrari and Red Bull, but made clear that Ricciardo was aware of the long-term project in play at Enstone.

"It’s maybe a little bit too soon, because we are not there [at the front]," Prost said.

"But when we talked to Daniel, it was a very frank discussion that means he knows everything. He has seen everything. He knows that he cannot be world champion next year. We are going to be better, for sure, but it will take time.

"We were a bit surprised when he said 'yes, I want to come.' He’s going to also allow us to push the team to become even better and better all the time. So there’s a little bit more pressure on the team because of him. But in the end it’s positive pressure."

Prost said he believes that Ricciardo could help lift Renault out of the close midfield fight and take a step towards the leading teams in F1.

"As a driver, you can see when you are in a top team, and then you have an average team, there is a lot of small differences that can make obviously the difference in competitivity. A driver like him can help," Prost said.

"We need to put everything we can together to become a top team, and he is part of that. The marketing side, he’s good value. He’s a funny, funny guy. If you talk about Daniel, inside Formula 1, outside Formula 1, he’s never controversial.

"For me, he is one of the best drivers to overtake people. He’s very competitive. He’s got more points than his teammate very, very often, like Max, who is considered maybe one of the best.

"He’s a top guy, and in a team like Renault, you need to have a good ambience. We need to have two drivers working well together, getting along without any problems.

"I’m sure with Daniel and with Nico, it’s going to be a good team."