Kostornaia takes victory at the NHK Trophy from Rika Kihira and Olympic champion Alina Zagitova, with all three making next month's Grand Prix Final
Alena Kostornaia dug deep to complete victory at the NHK Trophy in Sapporo on Saturday.
The 16-year-old fell in the warm-up, and had to watch strong skates from her nearest rivals Alina Zagitova and Rika Kihira, before taking to the ice.
But she responded to the pressure and, apart from an error on a second triple Axel, skated superbly to win the free skate and make it two wins out of two in her first senior Grand Prix of Figure Skating season.
Kostornaia told ISU.org afterwards, "I am very happy to have performed a good program. There were mistakes, but overall it was still good.
"I’m pleased to have achieved a record score in the short program, and I would like to set records also in the free skating and total score."
Kostornaia's triumph means all six Grand Prix events have gone to Russian first-season seniors trained by Eteri Tutberidze as Alexandra Trusova and Anna Shcherbakova also won both their respective assignments.
Kihira and Zagitova both had season's best free skates to fill the podium spots and qualify for next month's Grand Prix Final with Bradie Tennell of the United States completing the six-woman line-up in Turin.
Alina Zagitova was the first of the podium contenders to skate, and it was a much better day at the office for reigning world and Olympic champion.
The PyeongChang 2018 gold medallist was down in fourth after a disappointing short program.
The 17-year-old looked far more confident in her jumping on Saturday, and while she admits she "can't skate like Carolina Kostner yet!", Zagitova is a more rounded skater than when she won Olympic gold.
She certainly looked much happier in the kiss and cry as she received a season's best score of 151.15 for a total of 217.99 and a place in the Grand Prix Final.
Zagitova told ISU.org, "After the short program I was upset, of course. But I pulled myself together for the free skate thanks to my coaches finding the right words. In the program, I was just thinking from one element to the next what I need to do."
After her second in the short program, Rika Kihira had another good day in the free skate as she put up a strong defence of the title she claimed in 2018.
The Japanese again chose not to unveil her quad Salchow, but her trademark triple Axel was in fine working order and she just beat Zagitova's free skate score with 151.95 for a season's best total of 231.84.
The home crowd was delighted with her performance as she booked a return to the Grand Prix Final which she won last year.
Kihira admitted there were "small mistakes", but told ISU.org she was happy she "could do something that was close to my personal best."
She added, "It was a tough competition and I believe the Grand Prix Final will be even tougher."
Then came Kostornaia, who set a world record in Friday's short program.
Despite a fall in the warm-up, she started with a spectacular triple Axel-double toe loop combination before under-rotating her second triple Axel.
That lapse did not seem to affect her. A triple flip-triple toe loop combo was the highlight in a routine high on artistry and elegance.
It resulted in a score of 154.96 to take a free skate and a total of 240.00 for victory by just over eight points
Having backed up her victory at the Internationaux de France on her senior Grand Prix debut, it looks like Kostornaia will be battling with her two training partners for top spot on the podium in Turin.
Earlier, Yuhana Yokoi gave the home crowd reason for cheer with a season's best free skate of 126.87 which took her into the lead from reigning European champion Sofia Samodurova.
She eventually finished fourth ahead of fellow Japanese Mako Yamashita with Samodurova down in sixth.
American Karen Chen slipped from third overnight to ninth after a couple of falls in her free skate.
While Yuzuru Hanyu's men's singles victory was the undoubted highlight for the locals, the performance of the day came from ice dance world champions Gabriella Papadakis and Guillaume Cizeron who ended up rewriting the record books three times in Sapporo.
After their home triumph at the Internationaux de France in Grenoble, the Olympic silver medallists just seem to get better and better.
Following their world record rhythm dance on Friday, the French duo set another world record in the free dance with a score of 136.58, beating their 135.82 from this year's World Team Trophy.
Their total of 226.61 was over three points better than the 223.13 they achieved at the World Team Trophy.
It is hard to see anyone getting close to them in the Grand Prix Final which they missed last year after Cizeron's early-season back injury ruled them out of the NHK Trophy.
Ice Dance Grand Prix Finalists: Papadakis/Cizeron (FRA), Stepanova/Bukin (RUS), Victoria Sinitsina/Nikita Katsalapov (RUS), Piper Gilles/Paul Poirier (CAN), Madison Hubbell/Zachary Donohue (USA), Madison Chock/Evan Bates (USA).
Starting the day with a 10-point lead after a world record short program, the world champions from Saitama in March were not quite at their best in the free skate.
The Canadians will also be in Turin, as will Russia's world junior champions Anastasia Mishina and Aleksandr Galliamov who finished third after winning on their senior Grand Prix debut at the Internationaux de France.
Pairs Grand Prix Finalists: Sui/Han (CHN), Moore-Towers/Marinaro (CAN), Mishina/Galliamov (RUS), Aleksandra Boikova/Dmitrii Kozlovskii (RUS), Peng Cheng/Jin Yang (CHN), Daria Pavliuchenko/Denis Khodykin (RUS).