Thierry Neuville of Hyundai edged Ford's long-time leader Elfyn Evans by just 0.7 seconds to win a thrilling Rally of Argentina on Sunday which left the beaten Welshman feeling "sick".
It was a second consecutive rally win for the 28-year-old Belgian after his success in Corsica last time out while Evans was denied a first career triumph after seeing his lead gradually whittled away over the weekend.
Estonia's Otto Tanak was third, 30 seconds back while defending world champion Sebastien Ogier of France was fourth at 1min 24sec behind the winner.
"I gave it everything on the last stage," said Neuville. "My tyres were not in great shape because I had attacked a lot on the two previous stages. We gave it the maximum."
Going into Sunday's final stage, Welsh driver Evans still led by 0.6sec in his Ford Fiesta, which had suffered a series of tyre and technical problems on Saturday.
But 28-year-old Neuville, who had been 11.5sec behind overnight, flung his Hyundai down the famous El Condor mountain to overhaul the heartbroken Welshman and claim a fourth career championship win.
"I'm sick of losing by such a small gap, it's hard to swallow, but we'll be stronger," said Evans, who added that an accident on Saturday had dented not just his car but also his hopes of winning.
"I made a little mistake, I hit a bridge, it's probably what made the difference, but I will have to learn from it."
Ogier, racing for the private Ford M-Sport team after Volkswagen pulled out of the championship last year, still leads the overall standings after five rounds on 102 points.
He is 16 points ahead of Finland's Jari-Matti Latvala, in a Toyota, and 18 in front of Neuville.