Dakota Ditcheva ran through Jena Bishop in one round in Tennessee to reach the final of the 2024 PFL flyweight series.
Ditcheva, 26, dropped Bishop with a powerful knee before landing a hammer fist on her opponent.
The Briton invited Bishop back to her feet before the referee stopped the contest.
Ditcheva competes in the £781,000 ($1m) PFL final later this year and will face Brazilian Taila Santos for the world title and prize money.
Ditcheva won PFL’s European flyweight title last year, which carried a £100,000 prize.
Her victory over Bishop is her fourth first-round finish in a row and improves her record to 13 wins, 11 knockouts and no defeats.
Normally a cool customer in the cage, Ditcheva was visibly riled during and after the fight.
When she first knocked down Bishop, she backed off and beckoned the 38-year-old back to her feet.
Bishop got back up, but immediately started to retreat to the cage wall and went down again under a barrage of punches.
Ditcheva then made a shush gesture to Bishop and her team and explained in the post-fight interview she was being targeted on social media by critics.
“I think I’ve proved enough just there. We don’t do no split decisions around here,” she said.
“It’s irritating a lot of people [that I keep winning].
“Jena, her whole team, been talking, tagging me in stories the whole tournament. She’s going to join a list of cans now so take a seat.”
As well as being one step from her first world title as a professional fighter, Ditcheva’s win confirmed she is one of the sport’s rapidly rising stars.
The finish was her seventh in a row.
Santos, 31, swapped the UFC for the PFL earlier this year and defeated former Bellator champion Liz Carmouche on points to reach the final.
The PFL use a series format in the United States, with a group stage followed by the semi-finals, then the end of year finals.
Santos has 22 wins and just three losses, but Ditcheva is not concerned about the gap in experience.
“A very tough girl who has proved herself,” Ditcheva said.
“This is the fight everyone wants to see. I’ll be there to put on a show. It’s not going to be another boring three-rounder, not when I’m involved.”
