Max Verstappen will know within "one or two" races next year if he will stay at Red Bull in 2021.

That is the view of former Red Bull driver Robert Doornbos.

2020 is the final year on Verstappen's current contract, and he has made noises about potentially switching to a faster top team for 2021.

"Nothing will happen in 2020," Doornbos told Ziggo Sport. "Max can't go anywhere yet.

"After that it will be a difficult choice, because you simply cannot see into the future.

"Max actually has the choice of two other teams, or three if you include McLaren. They've done extremely well and can become a serious team when they go to Mercedes engines.

"One thing is for sure and that is that Mercedes will not continue to dominate Formula 1 for another four years."

However, Doornbos thinks it is possible that Red Bull-Honda will succeed in retaining Verstappen beyond 2020.

"It's important for them to develop that car as well as possible next winter," he said.

"Max wants to see a good car next year if he is going to be convinced to stay. Max will be able to tell what kind of car he has after one or two race weekends.

"Based on that, he will make his choice quickly."

Verstappen, 22, is hopeful Red Bull-Honda can step up to the top two teams in 2020.

"We already have many ideas for next year about how we can make ourselves stronger," he said.

"Some things have worked well this year, some a little less, but there are always things that could be better. I always try to analyse everything that could be improved.

"I think we know what went wrong this year and have taken measures for next year, so we are going to find out," Verstappen added.