F1's current top teams will remain unchallenged until at least 2021.

That is the view of Romain Grosjean, a driver for the small American team Haas.

Thanks to its Ferrari collaboration, Haas is tipped to continue to challenge right behind the top teams Mercedes, Ferrari and Red Bull in 2019.

But Grosjean doubts any team will be able to actually beat the top three, even if the aerodynamic rules are changing this year.

"Formula one needs to improve the chances of other teams winning races, but I do not think it will happen before 2021," he is quoted by Corriere dello Sport.

"Ideally it would be nice to have more teams fighting for victory, because what sense does it make that it is always the same drivers?

"But at the moment, I think it will be the same thing. I do not think we will beat Red Bull, Ferrari or Mercedes this year," Grosjean added.

However, the Frenchman says the battle behind the big three will nonetheless be close.

"Renault will be strong and you never know about McLaren. It's big team that can always come back," he said.

"Racing Point is putting a lot of money into the team, and Toro Rosso is moving closer to Red Bull with the technical partnership, so there are many people who would like to be best of the rest," added Grosjean.