Charles Leclerc's arrival at Ferrari will be one of the most fascinating aspects of the 2019 season.

That is the view of 2016 world champion Nico Rosberg, referring to the fact that Sebastian Vettel will be joined at Ferrari next year by the 21-year-old youngster.

Many think that with his friend Kimi Raikkonen leaving, Vettel will be hard pressed to fend off Leclerc's challenge in 2019.

"I'll switch on the TV just to see the fight between the two Ferrari guys," German Rosberg told Italy's Autosprint.

"Leclerc is so strong. And Vettel is coming out of a difficult year. He will have to remain very focused and give his all if he wants to remain the Ferrari leader.

"Leclerc is not Raikkonen," Rosberg added. "It puts a lot of pressure on him."

In fact, Rosberg thinks Vettel-Leclerc reminds him of the explosive Alonso-Hamilton combination of 2007 at McLaren.

"In some ways it's like the revival of that but with some differences. Vettel is not as difficult as Alonso while Leclerc is not a warrior like Lewis," he said.

But Rosberg thinks the biggest problem for Vettel could be his inability to change his approach in order to fend off the Leclerc challenge.

"If you have too much confidence in your abilities, as he does sometimes, you're not ready to change that attitude," he said. "That's what I suspect of him. That he is not capable of modifying his approach."