London - Valtteri Bottas has what it takes to succeed with Formula One champions Mercedes but he will also have to show next season that he deserves to be there, according to team boss Toto Wolff.
The Finn failed to win a grand prix this year and ended up fifth overall while British team-mate Lewis Hamilton took 11 wins and became only the third driver to win five world championships.
"Every racing driver in a Formula One car has to look over his shoulder. It is a very brutal sport where only the best ones survive and they are very well aware," Wolff told Reuters.
"They have made the selection of the top 20 racing drivers in the world and every single year they have to justify that they deserve the place. It is not only valid for Valtteri but all the others as well."
Mercedes has 22-year-old Frenchman Esteban Ocon as its reserve driver for 2019 after he lost his race seat at Force India, now renamed Racing Point, to Canadian Lance Stroll.