Gaines is a former college swimmer who defends respect for biological sex in sports after losing races to transgender swimmer Lia Thomas in the past,

Algeria's Imane Khelif, one of two Olympic boxers to be disqualified from the 2023 World Championships for failing a gender test, won her debut bout after her opponent was forced to retire just 46 seconds into the fight.

Khelif advanced to the quarter-finals of the women's -66kg division after landing two heavy shots on Italy's Angela Carini, who was bloodied and unable to continue with a badly bruised nose.

After receiving a powerful right to the face from Khelif, Carini decided to leave the ring. The Italian raised her arm after the blow and went to her corner to talk to her trainer. The trainer waved for the referee to stop the fight.

In front of dozens of journalists, she fell to her knees and sobbed before bursting into tears again. "My nose really hurts and I said: 'Stop. It's better not to continue. My nose started dripping (with blood) from the first punch," she said.

The 25-year-old added: "I fight a lot with the national team. I train with my brother. I have always fought men, but today I felt too much pain. She hit me twice and I couldn't breathe. Retiring was a gesture of maturity, not surrender. That is for the IOC to judge".

Her coach, Emanuele Rezini, pointed out that "the Algerian is here because the IOC took this decision, which is very difficult to take because the case is complicated".

The International Olympic Committee (IOC) has cautioned against a "witch-hunt" following backlash over its decision to allow two boxers, initially banned for being deemed biologically male, to compete as women at the Olympics. 

Earlier on Thursday, the Algerian Olympic Committee (COA) condemned what it called "malicious and unethical attacks by certain foreign media against our outstanding athlete Imane Khelif". The COA denounced "totally unfair" "lies".

The controversy surrounding Imane Khelif goes back a long way. At the 2023 World Championships in New Delhi, the International Boxing Association (IBA) decided to subject her to tests that showed she had XY chromosomes,

"This test conclusively showed that both athletes did not meet the required eligibility criteria and were found to have competitive advantages over other female competitors," the IBA said then. Both boxed in the women's division at the Tokyo Olympics three years ago, where the Algerian finished fifth.

And from Italy, after the match, came the angry reaction of Prime Minister Giorgia Meloni, who denounced a match that was "not on equal terms" according to her. "I don't agree with the IOC. I believe that athletes with male genetic characteristics should not be allowed to compete in women's events," she said at a meeting with Italian athletes in Paris.

 At the time, Umar Kremlev, president of the International Boxing Association (IBA), asserted that the tests showed the athletes, including Khelif and Yu-Ting, had "XY chromosomes."