"Withstanding pressure like that is not so obvious, even if there were some difficulties at times. But it is still a quite impressive maturity."
Vettel refused to cede to Leclerc in Russia, forcing Ferrari to put the Monegasque back ahead at the pit-stop phase, only for the whole plan to go up in flames when Vettel retired and Mercedes benefitted from the subsequent VSC period.
"It's a complicated situation of management," he said.
"With his experience, Vettel was considered the number one in the team, so it's hard to manage that. I think it's going to be difficult, especially next year.
"I think Ferrari will be strong next year and they will have to deal with the fight between Charles and Sebastian. If the car is good and they are both fighting over the title, that could give it to Mercedes."