Former F1 world champion Jacques Villeneuve believes Ferrari should offer Kimi Raikkonen a new contract for 2019 instead of promoting Sauber driver Charles Leclerc alongside Sebastian Vettel.
Ferrari has yet to confirm its driver line-up for 2019, although reports earlier this year claimed a deal was done for Leclerc to replace Raikkonen.
Vettel has a contract at the team until the end of 2020 and Villeneuve is concerned a young driver like Leclerc would struggle against the four-time champion.
"Look at the work [Kimi's] been doing," he told F1's official podcast Beyond the Grid. "He's third in the championship, he's often quicker than Vettel and when he's not he's just a tenth behind. He's paramount in the development of the car. The whole team works fantastically well now.
"Put a young 'cub' next to Vettel and what will Vettel do? He'll try to eat him alive. Either he will destroy the young cub or it will end in tears and the whole team will end up going slower within two years. That's not constructive."
Villeneuve believes Leclerc needs another year to develop at Sauber, which is now closely linked to Ferrari though its Alfa Romeo sponsorship.
"Charles is still making a few mistakes," he said. "It would be amazing for him [to go to Ferrari], but it would be two years of Ferrari preparing him.
"Ferrari, like Mercedes, is not a team to prepare drivers. It's a top team. Top teams they pay for the drivers when they are at their best and when they want them. That's why you have junior teams, to prepare them."