Mercedes F1 boss Toto Wolff says he is worried a disappointing 2018 campaign has taken its toll on Valtteri Bottas.
Bottas, who was forced to play a supporting role to teammate Lewis Hamilton’s championship bid after falling out of title contention himself following a difficult start to the year, finished a distant fifth place for the fourth successive race in the season-ending Abu Dhabi Grand Prix.
Wolff revealed Mercedes disovered an issue on the rear right brakes of Bottas’ W09, which he says instigated the second stop.