Sebastian Vettel's outside hopes of delaying Lewis Hamilton's coronation as a five-time world champion suffered a first-lap setback at the US Grand Prix when he collided with Daniel Ricciardo.
Vettel, in a Ferrari, had started in fifth place in Sunday's race but his collision with Red Bull's Ricciardo sent him down to 15th place.
Pole-sitter Hamilton will take the title if he gathers eight more points than Vettel.
Hamilton lost first place to Ferrari's Kimi Raikkonen on the opening lap.
By lap 18, Vettel had recovered to fifth place.