James Galloway moderator 5pts Valtteri Bottas needs to discover a "killer" instinct to get closer to Lewis Hamilton in 2018, according to Mercedes chief Toto Wolff."I think Lewis all year has been rock and roll and Valtteri has recovered slowly but still needs the tick of a killer," said Wolff after Bottas was beaten to victory by Sebastian Vettel in Brazil. "But you must not underestimate that in traffic against the Ferraris it was really difficult."He added: "He is not satisfied with [the Interlagos] race because Lewis was rock and roll this year it was difficult for him to shine. He will recover now before Abu Dhabi and start afresh next season."