Alain Prost has cautioned Ferrari that they must control their embattled drivers or risk handing another world title double to Mercedes during the following season.

The four-time world champion, Alain Prost, who was embroiled in one of Formula One's sternest in-team competitions when he and Ayrton Senna were team-mates at McLaren in the late 1980s, said Ferrari faced a "complex state of management".

The Frenchman said he could anticipate the battles between four-time winner and team leader Sebastian Vettel and young aspirant Charles Leclerc costing them the championship and passing it to Mercedes once more.

"With his experience, Vettel was considered the number one in the team, so it’s hard to manage that," Prost told. "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."

Ferrari have revealed marvelous speed and form since F1’s European summer break in August. It has taken 5 succeeding pole positions and locking three victories. Leclerc has won two times and Vettel once.

But their glory has been hindered by their drivers' competition as shown in Russia. There Vettel ignored team orders, and in Japan, he took pole, but had a bad beginning and Leclerc crashed with Max Verstappen.