Lewis Hamilton, on 346 points, has a lead of 70 over his four-time champion rival with a total of 75 remaining to be won from the last three races
Lewis Hamilton was made to wait for his fifth Formula One world championship Sunday after the Mercedes driver finished only third in a U.S. Grand Prix won by Ferrari veteran Kimi Raikkonen.
The victory was the 21st of the 39-year-old Finn's career and first since the Australian Grand Prix of March 2013, a gap of 113 races dating back to when he was racing for now-defunct Lotus.
Red Bull's Dutch youngster Max Verstappen took a surprise second after starting 18th in a thrilling finale with the top three cars running nose-to-tail and separated by just 2.1 seconds at the chequered flag.
Ferrari's Sebastian Vettel, Hamilton's only title rival, spun down to 15th on the opening lap but fought back to finish fourth - a result that means the championship remains mathematically open going into Mexico next weekend.
Hamilton, on 346 points, has a lead of 70 over his four-time champion rival with a total of 75 remaining to be won from the last three races.
That means even if Vettel wins in Mexico, the Briton need to finish only seventh to be sure of the title but Sunday was still a missed opportunity for Mercedes, who got their tyre strategy wrong.
Hamilton pitted early during a virtual safety car period but had to make two pitstops to his rivals' one, losing time on fading tyres before being called in.
A late charge over the final 19 laps from fourth was not enough.
Team mate Valtteri Bottas helped by letting him through for third, but the Finn then lost out to Vettel as his tyres wore down and finished fifth.
Hamilton went wheel-to-wheel with Verstappen with two laps left but failed to make the move stick and ran wide at turn 18 after giving the Dutchman plenty of space.
The outcome had looked very different at the start, when Vettel, fifth on the grid, spun on the opening lap after making contact with Red Bull's Daniel Ricciardo in the battle for fourth place.
It was the second time in two races that the German had come off worse against a Red Bull - in Japan he had started eighth, dropped to 19th after a collision with Verstappen and fought back to sixth - and he seemed to have handed the title to Hamilton.
Congrats to Kimi, he did a great job today out there. A huge thanks to the fans for always making this such a special place to race. We keep working and will push forward to the next one in Mexico #USGP #F1 @MercedesAMGF1 pic.twitter.com/otpMJS0DhS— Lewis Hamilton (@LewisHamilton) October 21, 2018
Instead, he staged a solid recovery drive to delay the inevitable.
Ricciardo, who is leaving for Renault at the end of the season, made it easier for him by retiring with a power unit failure after eight laps while in fourth place.
Renault's Nico Hulkenberg finished sixth, ahead of Spanish team mate Carlos Sainz, with Force India's Esteban Ocon eighth before being disqualified for a fuel breach.
So too was Kevin Magnussen, ninth across the line for the U.S.-owned Haas team.
Their removal from the results lifted Force India's Mexican Sergio Perez to eighth, with Toro Rosso's Brendon Hartley ninth and Sauber's Marcus Ericsson 10th.
McLaren's Fernando Alonso retired after an opening lap collision with Williams' Lance Stroll, who was handed a drive-through penalty.