Charles Leclerc had a "clear impact" on Sebastian Vettel's performance in 2019.

That is the admission of Ferrari CEO Louis Camilleri, shortly after team boss Mattia Binotto said the pair will head into 2020 "on par".

"He (Leclerc) had a clear impact," Sky Italia quoted Camilleri as saying.

"You can't avoid it when you're a world champion and such a young guy has an incredible season."

It is clear that Vettel, 32, has lost his clear number 1 billing, but Binotto said the quadruple world champion will still play "a key role" in 2020.

"He has been in the team for many years and knows it well," he said.

"He has a lot of experience, he has won four world championships, and he was decisive in how we developed the car during the past season.

"There is no doubt that such a driver plays a key role in our project," Binotto added.

Binotto said car "instability" and "such a quick teammate" contributed to Vettel's high-profile struggle.

"The situation certainly gave Seb a headache," said the Italian.

"But he was very analytical about getting better. In the second half, when he was more comfortable in the car, Seb was at a very similar level in the race.

"Charles was quicker in qualifying," Binotto added.

Finally, Binotto said Ferrari cannot be considered a favourite for 2020, after the winter optimism last winter hit the team hard at the start of the season.

"We could see in Abu Dhabi that we are not the best car, so the favourites are the ones that have won the last six world championships," he said.

"The new chassis is ready and we are now passing the crash tests and the homologation. We have a few more sessions in the wind tunnel and then we will have the package we want to release for the Barcelona test."