The thrill of victory could not have been more evident on the face of Claressa Shields, especially after having spent the preceding two rounds facing potential defeat.

A burning desire to succeed ultimately propelled Shields to victory in her MMA debut, stopping Brittney Elkin in the 3rd round of their ESPN-televised main event Thursday evening at Ocean Casino Resort in Atlantic City, New Jersey. Shields admittedly entered the final round believing she was down on the scorecards though refusing to taste her first loss in any combat sports medium.

“I never doubted myself in a boxing match in my life. MMA is something like, it’s possible I can lose this first fight,” Shields admitted during her post-fight interview. “I don’t want to lose but all I could do was just try not to lose.

“I just had a never quit attitude every round. Whatever you do, I didn’t care if she got me in an armbar, I didn’t care if she got me in a triangle, do not quit.”

Shields (11-0, 2KOs in boxing; 1-0, 1KO in MMA) showed composure in the face of adversity throughout the bout, which served as part of the Professional Fighters League (PFL) with whom she signed a multi-fight contract last fall. Elkin (3-7 in MMA)—a brown belt in jiu-jitsu—put her size and experience to use, scoring multiple takedowns in rounds one and two though ultimately unable to defend against Shields’ ground-and-pound game.

“I feel like I am dreaming. This is crazy! This was hard,” noted Shields. “Every time I sat down in the corner, I was like ‘Damn, I lost another round.’ Came out for the second round, lost the second round. Then came the third round, coach said to not get taken down.

“She got me on the ground but she never hurt me. None of her punches hurt me. None of her armbars—nothing. When that third round came, I was there to destroy her. I went crazy after that. I was not losing.”

A winner’s mentality has always come natural to Shields, who went 77-1 in an historic amateur career that included back-to-back Olympic Gold medals in 2012 London and 2016 Rio. Shields’ lone defeat came in the 2012 AIBA World Boxing Championships prior to the 2012 London Olympics, dropping a decision to England’s Savannah Marshall at just 17 years of age. Despite the setback, Shields still qualified for the Olympics, capturing the first of two Gold medals before taking her talents to the pro ranks where she has claimed championships at super middleweight, middleweight and junior middleweight, in that order.

Shields came in just under the 154-pound limit for each of her past two boxing matches and is campaigning in the 155-pound lightweight division in PFL. She has lost fewer than five total rounds as a pro boxer but quickly found herself in a hole in her MMA debut.  

It was never going to be the end of her.

“I may have lost those two rounds but I was not losing this fight,” insisted Shields. “I sat there in the corner, they said ‘Go out there and get your KO.’ When he said that, I came out (and did it).”

Jake Donovan is a senior writer for BoxingScene.com. Twitter: @JakeNDaBox