Antonelli's race engineer admits title success came sooner than expected

Mercedes race engineer Peter Bonnington has said he did not expect Kimi Antonelli to reach Formula 1's championship heights so early in his career. Antonelli became the sport's youngest champion by finishing third at the Mexico City Grand Prix, beating Sebastian Vettel's record by more than three years.

Bonnington recalled describing Antonelli as a "diamond in the rough" during testing of previous cars, when he was on a 9,000 to 10,000-kilometre programme ahead of his debut. The engineer said he had thought it would take a few years to develop the 20-year-old, but progress came far more quickly than that.

Antonelli was initially expected to play second fiddle to George Russell, but adapted better to the W17 and new regulations. Bonnington said he only began to believe the title was possible during a five-round winning run, while keeping expectations quiet.