It was the 21st victory for Kimi Raikkonen'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.
Kimi Raikkonen's second stint with Ferrari has been long on frustration and short on victories.
That finally changed on Sunday at the US Grand Prix where the Finnish driver earned his first win in five years, while a good enough day from Ferrari and a late block from Red Bull's Max Verstappen denied Mercedes' Lewis Hamilton a fifth career Formula One championship.
A former world champion with Ferrari, Raikkonen hadn't won after his return to the team in 2014 while teammate Sebastian Vettel fought Hamilton for the championship the last two seasons.
"It's nice to win"
Raikkonen's most previous win had been with Lotus at the season-opening Australian Grand Prix in 2013.
He'd driven his Ferrari to three second-place finishes this season before Sunday's victory.
Success finally came with a muscular performance by both driver and car on a day when Hamilton could have clinched the championship with a sixth US Grand Prix in seven years.
Raikkonen seldom cracks a smile or shows much emotion, but he shouted an expletive on the team radio after the final lap. He was then his typical stoic self after a brief victory celebration at the podium.
"It's nice to win. It doesn't change my life," Raikkonen said. "The biggest difference is how people look @ you."
For Hamilton, a rare defeat in Austin means his fight with Vettel for the championship continues to next weekend at the Mexican Grand Prix. Hamilton finished third and Vettel was fourth to stretch Hamilton's championship lead 70 points with three races left.
Hamilton is trying to match Argentina's Juan Manuel Fangio, whose five championships in the 1950s rank second in F1 history. Only Germany's Michael Schumacher has more with seven.
Hamilton could have won the championship Sunday even without a race victory if he'd finished at least eight points ahead of Vettel.
The late blocking move by Verstappen and Vettel's charge past Mercedes' Vallteri Bottas in the final laps kept the championship alive.
Hamilton said he had to be cautious around Verstappen to avoid a collision.
"Championships are not won by doing silly mistakes. I gave him way too much space just be sure that I didn't get taken out," Hamilton said.
"The key to me was to make sure I finished ahead of Seb. I don't care when you win a championship, just that you win."
Verstappen started 18th after damaging his car in qualifying and worked his way through the field to finish second, his fourth podium finish in six races.
"At that turn, I was pushing as much as I could," Verstappen said. "I was really hanging on."
Hamilton started on pole position but quickly lost position to Raikkonen on the first turn. The Mercedes tried to squeeze Raikkonen to the inside on the bolt uphill out of the start, but the Ferrari nosed ahead into the left turn into the slingshot back downhill.
Vettel was under pressure from the beginning. He started fifth because of a three-spot grid penalty for driving too fast while under a red flag during a Friday practice.
Vettel at first looked like he tried to make up too much, too soon. A bump with Red Bull's Daniel Ricciardo caused Vettel to spin and dropped him to ninth, and the gap looked like it would be too much to overcome.
Raikkonen's ability to keep Hamilton behind him gave Vettel new life and the chance to make the late pass on Bottas.
Vettel "happy for Kimi"
"Really happy for Kimi," Vettel said.
Hamilton also questioned Mercedes' two-stop strategy. He changed tires 11 laps in when the race was under virtual safety car.
He had to pit again late and came out fourth, facing a 12-second gap that was too big to close.
"As a team, we clearly struggled," Hamilton said. "Performance-wise, we were definitely off."
Raikkonen won the season championship with Ferrari in 2008, a title that came down to the last race of the season. He rejoined Ferrari at a time the Italian team was lagging far behind Mercedes.
Raikkonen will be leaving Ferrari to join Sauber after this season, moving from car capable of winning to a team that is rarely competitive. Raikkonen said he has no hard feelings toward Ferrari.
"I'm very happy where I'm going. I won the championship with (Ferrari)," Raikkonen said. "As a driver I want different challenges."