ATLANTIC CITY, N.J. (AP) — From the squared circle to the cage, Claressa Shields simply can’t lose.

Shields made short work in her MMA debut of Brittney Elkin, and the two-time boxing gold medalist proved she might have a future in the sport with a TKO win on Thursday night in the main event of a Professional Fighters League card.

“I’m not losing this fight,” the undefeated boxer said.

A two-time Olympic gold winner, Shields proved in her 155-pound fight she’s just as adept at unleashing a beating in mixed martial arts. She shook off a slow first two rounds before she got Elkin on the ground and needed a few heavy shots to cause the decisive damage. She earned the win with a right hand from the top at 1:44 of the third round.

“I feel like I am dreaming. This is crazy,” she said.

Shields ditched some of the flamboyant costumes she’s worn in boxing (where she’s 11-0) for straight red trunks and top. She still wore her hair in a blue ponytail to raise awareness to the clean water fight that’s gone on for years in her hometown of Flint, Michigan.