A series of errors sent Rika Kihira sliding from second to seventh overall after the women's free skate at the ISU World Figure Skating Championships on Friday.
Sixteen-year-old Anna Shcherbakova, who led Kihira after the short program, secured the win in her worlds debut after scoring 152.17 points in the free skate to tally 233.17 points overall. She led an all-Russian top-three, the first time its skaters have swept the podium in the women's event.
Elizaveta Tuktamysheva scored 220.46 points and Alexandra Trusova had 217.20 to finish second and third.
Kaori Sakamoto was the highest-placed Japanese in sixth with 207.80 points, one spot above Kihira who ended with a 205.70-point total after managing just the ninth-best score in the free skate.
The results mean Japan has secured three slots in the women's field for next year's winter Olympics in Beijing.
Kihira's hopes of a maiden world title were dashed when both her triple axels turned into doubles, with her failing to land the second. Her triple lutz also became a double.
"I lacked the ability to make adjustments. It became a sorry display," lamented the 18-year-old, who also struggled with her spins and steps for her worst result at worlds in her three senior seasons.
"My body was asleep. I couldn't get the power to my legs...I need to train with much more difficult components. I need to push myself in everything."
Sakamoto was adjudged to have used a wrong edge in a triple lutz, as was the case during her short program, and her total stood 15.85 points off her personal best.
"I feel uneasy but I need experiences like these too," said the 20-year-old, who was fifth in her debut two years ago.
Satoko Miyahara, the runner-up in 2015 and third-place finisher in 2018, had a difficult outing on her 23rd birthday and ended up 19th, by far her worst result in five world championships appearances.
"In terms of technique, it wasn't a performance worth talking about," said Miyahara, who was kept off the ice with a right foot injury in December. "My condition wasn't so good. I feel I had that anxiety somewhere in my heart."
No spectators are allowed to attend the March 22 to 28 competition at the Ericsson Globe.
Russian skaters are representing the Figure Skating Federation of Russia team. The country has been banned from using its name, flag and anthem at the next two Olympics or at any world championships for the next two years as a penalty for widespread doping violations.