Curtoni beats the fog to win shortened World Cup downhill race
The 31-year-old took off second which allowed her to get best use of the course, which had been reduced to that of the Super-G, before it was draped in a heavy fog.
It was thickest in the middle of the course, reducing visibility in a discipline where speed often comes with risk.
The fog undoubtedly slowed the later competitors such as fellow-Italian Sofia Goggia who fractured her hand on the way down before finishing second, 0.29 seconds behind. The Swiss skier Corinne Suter was third 0.73secs behind Curtoni.
It is Curtoni's third World Cup victory, after the Super-G in Cortina d'Ampezzo earlier this year and the downhill in Bansko, Bulgaria, in 2020.
"I'm really happy," said Curtoni.
"With flat light it's tough and you need to be brave. I think I was able to put all my braveness on the slope today and it went well."
After winning the opening two races at Lake Louise, Goggia was a huge favourite, especially after her performance in Thursday's second training session when she was 1.10sec faster than second-best Lara Gut-Behrami who, on Friday, could only manage eighth.
Goggia, however, hit the third control gate with her left hand with post-race scans revealing a fracture of the second and third metacarpals in her hand. She was due to undergo surgery in Milan in order to try to start the second downhill on Saturday.
She leads the discipline standings, 80 points clear of 28-year-old Suter who continued her excellent year.
Suter was crowned Olympic champion in the discipline, ahead of 2018 champion Goggia, and won the Lake Louise Super-G and the Garmisch-Partenkirchen downhill.
"I didn't feel very, very comfortable so I tried to find the risk today," said the Swiss, who finished second and third behind Goggia at Lake Louise.
"You can't see the bumps and it's not so easy but I tried my best and when it stays like this (third place), I'm super happy."
Mikaela Shiffrin produced a fine run on the day, taking sixth place after starting in 22nd position.
The American still leads the overall World Cup standings, 59 points ahead of the Swiss Wendy Holdener and 85 in front of the Slovak Petra Vlhova, neither of whom competed on Friday.
The weather is expected to be better for Saturday's second downhill. The Super-G takes place on Sunday.
