Nico Rosberg held off Mercedes team-mate and title rival Lewis Hamilton to win a race-long battle at the Brazilian Grand Prix.
Hamilton fought back to close a seven-second margin after a spin at about one-third distance just as he appeared to be set to take the lead.
But Rosberg did just enough to hold him off in a tense final part of the race.
It reduces Hamilton's advantage in the title to 17 points, with 50 available in the final race in Abu Dhabi.
Nico Rosberg keeps Lewis Hamilton behind
"I'm very happy with the whole weekend," said Rosberg. "I've been feeling comfortable in the car and controlled the gap to Lewis in the race."
Hamilton can win the title by finishing second to Rosberg in Abu Dhabi on 23 November, even though double points will be on offer.
But the Englishman may rue a half-spin on lap 28 which, as it turned out, decided the race in Brazil.
Rosberg had made his second pit stop on lap 26, with Hamilton less than two seconds behind him.
Hamilton stayed out, setting the fastest lap of the race to that point and then deciding to do one more lap before his own second stop.
It should have been enough to get Hamilton past the German, but he dropped a wheel on to the white line at the entry to Turn Four, the Descido do Lago, and ran wide into the run-off area, half-spinning.
The incident cost Hamilton seven seconds, which he reduced to two over the course of their third stint.
Rosberg came in first for his final stop, on lap 50, with Hamilton making his a lap later, and their battle resumed with them half a second apart on lap 52, 19 from the finish.
Hamilton, clearly faster, stayed within a second of Rosberg for the remainder of the race but was never close enough to make a passing attempt.
Rosberg thus took his fifth win - his first since Germany back in July - while Hamilton has 10 victories.
"It was an amazing race," said Hamilton. "I had a great time.
"Obviously I made a big mistake in the mid-part of the race, but the car was fantastic and it was great to race with Nico.
"It's everything to play for in the last race."