Pirelli boss Mario Isola says he has been surprised by Charles Leclerc in 2019.

With just a single season at Sauber under his belt, Leclerc made his Ferrari debut this year at the age of 21.

He began the season as number 2, but has since challenged that hierarchy and put a cloud over quadruple world champion Sebastian Vettel's future.

"I have to admit that I would have expected a little more trepidation from him in his new environment, especially with a four time world champion as a teammate," Isola is quoted by Corriere dello Sport.

"Instead, he has proved to be a talent. Yes, he made some mistakes at the beginning of the season, but the fact that he always admitted them shows that he is a driver who wants to develop," he added.

As for Ferrari's season, Isola said: "There may be some regret about not having maximised some results.

"But there is also the knowledge that they will be able to start again in 2020 with a competitive machine."