Kayla Harrison, the two-time defending PFL women’s lightweight champion and the promotion’s most dominant fighter, is undefeated no more. Larissa Pacheco, who twice before had faced Harrison and had lost both times, got a stunning victory in her third crack at Harrison on Friday night in New York.

The fight was one of six weight division PFL season championship finals contested inside Hulu Theater at Madison Square Garden.

Harrison (15-1), a two-time Olympic gold medalist in judo, came in as an 8-1 betting favorite. She and the PFL were already making plans for next year, removing her from regular-season competition in order to book her in “superfights,” presumably with a step up in competition. Pacheco might have spoiled those plans.

The fight started well for Harrison, who scored an early takedown and threatened a submission for much of the first round. But Pacheco (19-4) withstood those difficult five minutes and fought back in the second round, using her powerful stand-up skills to land heavy strikes and utilizing strong takedown defense to turn the tide.

The fight appeared to be tied going into the fifth round, and Pacheco was the fresher fighter at that point. She landed some hard punches on Harrison, who eventually landed a takedown but could not capitalize.

All three judges scored the bout 48-47 in favor of Pacheco. Before this bout, Harrison had not lost even a single round in her career. Harrison is No. 8 in the ESPN pound-for-pound women’s top 10, the only PFL fighter in either those rankings or the divisional ones.

When Pacheco was awarded the championship belt and an oversized replica of a $1 million check, she credited her opponent for playing a role in getting her to where she now stands in her career.

“Just like Kayla said before: I’ve always made her a better competitor,” Pacheco said through an interpreter. “Well, she’s always made me a better competitor. She drove me to this moment.”