Katya and pro dancer Joe McFadden stunned the judges and viewers with their Argentine Tango.
The routine ended with an impressive lift that had the crowd in the studio on their feet.
Chatting on It Takes Two about the move, Katya revealed: "It seems I have this thing with the moves. Last year I had the Gangnam Style. I need to start getting ready for next year."
Lifting the lid on the secret of the lift, Katya told host Zoe Ball: "It's because of the heels. In rehearsals I had flats on and the balance was all over the place.
"I whacked the heels and I just tipped over. It worked. Needing to get to the final, we had to do something special."
Joe confirmed: "It went much smoother [live], in rehearsals it had gone wrong 90% of the time."
Meanwhile, Joe said of making it through to the final: "Not in a million years did I think I'd see this day.
"To have all that work over the last couple of months come to something, it feels absolutely amazing."
This weekend the final couples will each dance three times: Their showdance, a favourite dance from the series, and a pick from the judges.
Joe and Katya's showdance will be to You Make My Dreams by Hall & Oates while the judges have chosen them a Viennese Waltz to Somewhere My Love from Dr Zhivago. The couples' favourite choices will be revealed on the night.
This year there will be no eliminations in the final, with all four couples dancing until the end of the night where the winner will be announced.
Strictly Come Dancing 2017 airs Saturday night from 6:30PM on BBC One.