Henrik Kristoffersen of Norway won his sixth slalom in a stellar World Cup season, matching a feat previously achieved only by three of the biggest names in ski racing history.
Alberto Tomba was the last to win six slaloms in 1994-95, while Ingemar Stenmark did it in the 1970s and Marc Girardelli in the 1980s.
Kristoffersen, who was 1.10 seconds off the lead in third after the opening run of Tuesday's night race, defeated Marcel Hirscher of Austria by 0.61 seconds, and last year's winner, Alexander Khoroshilov of Russia, by 0.77.
Kristoffersen and Hirscher also came 1-2 in Kitzbuehel two days ago.
First-run leader Felix Neureuther of Germany straddled a gate and failed to finish.
"It was really tough," said Kristoffersen, who earned his first of 10 career wins here two years ago. "I had a mistake at the top. I saw Marcel, he was incredible, hats off. But I was fast. Now I have my second win in Schladming. That's cool."
Hirscher was only 22nd with a 2.59-second deficit after his goggles fogged up in the opening run but the Austrian posted the fastest time in the second leg.
An incredible result
"I never thought this was possible. It's an incredible result after what happened in the first run," Hirscher said. "Of course everything went in my favour in the second run. The course got worse. I squeezed out everything I had. I am grateful. Every race is like a final."
The Austrian said one of his technicians prepared his goggles wrongly. With the protective coating on the wrong side, they fogged up after a few seconds into his opening run.
"Where people work, mistakes are made," Hirscher said. "But it shouldn't happen of course."
The mishap gave him an early start in the second, which turned out to be an advantage. After a day of mild temperatures, the top layer of the Planai course weakened during the race and slowed later starters.
Hirscher led the final run by more than half a second, and the Austrian smiled in disbelief while standing in the leaderboard area for almost the entire second run.
It was Hirscher's 40th top-three finish in a slalom, which gave him a share of third place on the all-time list behind Stenmark (81) and Tomba (57).
A trio of Canadians failed to complete the first run: Trevor Philp, Phil Brown and Erik Read.
In the opening run, Neureuther showed his old strength in slalom and built a commanding 0.53-second lead.
Neureuther won nine career slaloms and finished runner-up to Hirscher in the discipline season standings for the past three years, but had only one top-three finish this season.
"All season, I haven't had that feeling from previous years," said the German, adding he felt more comfortable after switching ski boots during training on Monday.
Kristoffersen's victory was the 15th by a Norwegian man this season. In the past 10 years, no nation has won more races in a single season.
Kristoffersen, who has scored 680 of a possible 700 slalom points, extended his lead in the discipline standings, 180 clear of Hirscher.
The Austrian, however, overtook Aksel Lund Svindal of Norway on top of the overall standings. Hirscher has 969 points, Svindal 916. Svindal was out for the season, leaving Kristoffersen, with 871, as Hirscher's main rival in the Austrian's quest for his fifth straight overall title.
The men's World Cup travels to Garmisch-Partenkirchen for a downhill and a giant slalom this weekend.