Tuktamysheva scored 81.53 points on another compelling performance skating clean in a typically impassioned routine.
Three skaters who we could potentially see on an Olympic podium at the Beijing 2022 Winter Olympics top the standings before Sunday's decisive free skate.
Read on for a full wrap of everything that happened today.
Tuktamysheva takes over
The 24-year-old proved once more that she is a contender for one of three Olympic berths for the Russian Figure Skating Federation with a sensational performance in the Espoo Metro Areena.
Tuktamysheva achieves an expression of her music that her younger counterparts strain to match, and her show-stopping short routine to Tango Oblivion had the crowd in raptures.
The technical elements were executed with speed and precision: A brilliant triple Axel was backed up by a triple Lutz-triple toe combination and a triple flip - all clean.
Her artistry was off the scale, the crowd loving every second. Her 81.53 score a recognition of her day's work.
The 2015 World and European champion has her sights set on an Olympic medal in China this February despite the fierce competition within the ranks and this short program win is another sign that she has what it takes.
Kostornaia proves she's over it
Now 18, there was a new maturity to Kostornaia's skating, she connects with the music more (Am I The One - by Beth Hart), and her double Axel, triple Lutz, triple flip-triple toe combo technical elements were close to perfect.
When her score of 78.61 flashed up on screen she looked slightly stunned, considering that Valieva had fallen on her triple Axel and still scored 74.93, but she was in first place before Tuktamysheva stepped up.
Kostornaia claimed the women's title here at the 2019 Finlandia Trophy and the 2020 European champion will feel she can emerge victorious tomorrow too.
Kamila Valieva overcomes fall on first jump with a fine short program
Kamila Valieva recovered well from a fall on her first jump (atriple Axel) to execute a triple flip and a wonderful triple Lutz-triple toe loop combination to score big with 74.93 points.
Skating to In Memoriam, the 15-year-old was elegant with a high degree of technical difficulty delivered at speed.
Yes, she looked disappointed afterwards, regretting that fall on her first jump. But the way she held it together to nail the rest of the program was a measure of her mental strength.
This teen sensation packs a quadruple jump or two in her arsenal, and while we didn't see that quad toe on Saturday, don't rule it out for Sunday.
Elsewhere, United States skater Karen Chen is sixth with 67.50 points behind Georgian Anastasiia Gubanova in fourth and Belgium's Loena Hendrickx in fifth.
Chen performed her short program to LaCena and the USA's other skater Amber Glenn had a disappointing day after a slightly under-rotated triple toe in her combination and a fall on her triple Axel.
But there were some positives including a nice triple loop as she performed to Circles/Experience, and tomorrow is another day.
Ice Dance: Papadakis/Cizeron reign the rhythm
Fresh off an imperious French Masters title win in Epinal on 2 October, PyeongChang 2018 silver medallists Gabriella Papadakis and Guillaume Cizeron were back on the ice in Espoo and back dominating once more.
They scored 85.58 points in Saturday's rhythm dance to lead the way ahead of Sunday's free dance.
After a 20-month absence that included pulling out of the 2021 world championships in Stockholm earlier this year, the French duo put in a compelling performance and are revving up for this Olympic season.
They received a huge welcome from the crowd in the Espoo Metro Areena and returned all that energy with a beautiful interpretation of John Legend's Made to Love and You & I.
All that on-ice chemistry and natural understanding earned over years of skating together were on full show, and they look strong contenders for another Olympic medal in February.
The Finlandia Trophy 2021
The Finlandia Trophy is the fourth of nine Challenger Series events is and takes place in Espoo, Finland from the 6th-10th October, where Jason Brown has already won the men's event.
It's been a packed schedule crammed with world-class talent in Espoo where the organisers had to add an extra day due to the number of athletes who signed up, in part due to the cancellation of the Nepela Memorial (the previous Challenger Series event).
Skaters from across the world have provided thrilling entertainment, including Sofia Frank from the Philippines, Australian Victoria Alcantara and Chilean skater Yae-Mia Neira.
Sunday 10 October is the final day, stay with Olympics.com for all the results and highlights.