Jacques Villeneuve has changed his tune about the Formula 1 debut this weekend of his 18-year-old Canadian countryman Lance Stroll.

Earlier, the 1997 world champion defended Stroll's arrival at the highest class of motor racing at such a young age.

However, he has now told Germany's Auto Bild: "He's so smart and talented, but I'm sorry - at the age of 18, he's too young for Formula 1.

"What Williams is doing is absolute madness. Stroll has a wild driving style and this could be dangerous.

Stroll will make his debut in Melbourne on Sunday, moving Villeneuve to suggest that the teen will have to rely heavily on the help of his experienced teammate.

"Williams needs [Felipe Massa] more than ever," said Villeneuve.

"I guess Felipe knows already that he's going to be like a driving instructor for Stroll."

Williams technical boss Rob Smedley said recently that the team will give Stroll time to get up to speed in F1, and the youngster agrees that he will need to adjust.

"I have no expectations for this first race," he told the Journal de Montreal in Melbourne.

"Finishing in the points would be nice, but I think it will take me half a season to understand how it really works.

"If it happens before that and I get good results from the start, I will be the first to be satisfied."

Williams finished fifth in the 2016 constructors' championship.