Max Verstappen is not ready to declare himself a real challenger for the 2019 title.

His boss at Red Bull, Dr Helmut Marko, has named the Dutchman alongside Lewis Hamilton and Sebastian Vettel as the main three contenders this year.

When asked if he agrees, Verstappen told Ziggo Sport: "It's just so difficult to say."

Red Bull has switched from customer Renault engines to works Honda power for 2019.

"The most important thing is that we are consistent this year, and whether that is enough for the world championship, I don't know.

"I'm a realist and an optimist and it's hard to say," Verstappen, 21, added.

However, he says he is happy with Honda.

"Not to say something against anyone else, but this engine is much more logical. It (the package) just looks super tight -- really beautiful," said Verstappen.