Imane Khelif of Algeria won her opening Olympic boxing bout Thursday when opponent Angela Carini of Italy quit after 46 seconds.
Khelif was disqualified from the 2023 world championships after failing an unspecified gender eligibility test, and her presence at the Paris Olympics has become a divisive issue.
There were only a few punch exchanges before Carini abandoned the bout, an unusual occurrence in Olympic boxing. Carini's headgear apparently became dislodged twice before she quit.
Carini refused to shake Khelif's hand after the decision was announced, and she cried in the ring before leaving.
"First, I thank all the Algerian people, after this first victory," Khelif said. "I hope to achieve a second victory to secure a medal, and then think about the gold medal. I tell the Algerian people that I am working to provide the best I can in order to make them happy."
A tearful Carini said she quit because of intense pain in her nose after the opening punches. Carini, who had a spot of blood on her trunks, said she wasn't making a political statement and was not refusing to fight Khelif.
"I felt a severe pain in my nose, and with the maturity of a boxer, I said 'enough,' because I didn't want to, I didn't want to, I couldn't finish the match," Carini said.
Carini said she is not qualified to judge whether Khelif should be allowed to compete but had no problem fighting her.
"I am not here to judge or pass judgment," Carini said. "If an athlete is this way, and in that sense it's not right or it is right, it's not up to me to decide. I just did my job as a boxer. I got into the ring and fought. I did it with my head held high and with a broken heart for not having finished the last kilometer."
Italian boxing coach Emanuele Renzini said Carini had been given the option to back out of the bout.
"I asked her, 'Angela, if you don't want to go up, let's not go,'" Renzini said. "But she told me no, 'This is my Olympics, I struggled to be here, I want to fight for my medal.' So she was very determined to do it.
"I supported her. I didn't imagine such an outcome. She never had any doubts. She wanted to fight."
Khelif is an accomplished amateur who won a silver medal at the International Boxing Association's 2022 world championships. The same governing body disqualified her from last year's championships shortly before her gold medal match because of what it said were elevated levels of testosterone.
The 25-year-old entered the ring at the North Paris Arena to a chorus of cheers, but the crowd was confused by the bout's sudden end.
Khelif and Lin Yu‑ting of Taiwan have been under scrutiny for their presence in Paris after years of amateur competition. Lin won IBA world championships in 2018 and 2022, but the governing body stripped her of a bronze medal last year because it said she failed to meet unspecified eligibility requirements in a biochemical test.
Khelif was ruled eligible to compete in Paris, a competition run by the International Olympic Committee.
The Algerian Olympic Committee issued a statement Wednesday condemning what it termed "lies" and "unethical targeting and maligning of our esteemed athlete, Imane Khelif, with baseless propaganda from certain foreign media outlets."
Lin begins her Paris run Friday, fighting Uzbekistan's Sitora Turdibekova in her opening bout after receiving a first-round bye as the top seed in the 57-kilogram category, although Olympic seeding is frequently unindicative of the top medal contenders in a division.
Khelif could clinch an Olympic medal with a victory in her quarterfinal bout Saturday against Anna Luca Hamori, Hungary's first Olympic boxer. Hamori expressed no concern about fighting Khelif, saying "I'm not scared."
Khelif and Lin are two-time Olympians who fought in the Tokyo Games with no controversy. Lin has been an elite-level amateur boxer for a decade and Khelif for six years. They were allowed to compete in Paris by the IOC task force, which has run the past two Olympic boxing tournaments.
The IOC on Tuesday defended the women's right to compete. Olympic boxing reached gender parity for the first time this year, with 124 men and 124 women competing in Paris.
"Everyone competing in the women's category is complying with the competition eligibility rules," IOC spokesperson Mark Adams said. "They are women in their passports, and it's stated that this is the case that they are female."
Several sports have updated their gender rules over the past three years, including World Aquatics, World Athletics and the International Cycling Union. The track body also last year tightened rules on athletes with differences in sex development.
But the IOC said it made its eligibility decisions on boxers based on the gender-related rules that applied at the 2016 Rio de Janeiro Olympics.
"What I would say is that this involves real people and we are talking about real people's lives here," Adams said. "They have competed and they continue to compete in the women's competition. They have lost and they have won against other women over the years."
The IOC is in charge of boxing in Paris because the IBA has been banned from the past two Olympics because of years of governance problems, a lack of financial transparency, and many perceived instances of corruption in judging and refereeing.
The IBA issued a statement Wednesday in which it said both boxers did not have a "testosterone examination" last year but were "subject to a separate and recognized test" for their disqualification. The IBA said the test's "specifics remain confidential" and refused to explain it.
IBA president Umar Kremlev also posted an incendiary video on social media in which he criticized IOC president Thomas Bach, the opening ceremony, and the decision to allow Khelif and Lin to compete.
Women boxers have been asked about Khelif and Lin repeatedly this week. Many have expressed concern, while others have urged more consideration of an obviously complicated issue.
"I don't agree with that being allowed, especially in combat sports as it can be incredibly dangerous," Australian middleweight Caitlin Parker said. "But right now, my focus is on getting through each fight. It's not like I haven't sparred with guys before, but it can be dangerous for combat sports and it should be seriously looked into. It is good that these things are coming out and it's being put under the spotlight to be looked into further.
"Biologically and genetically, they are going to have more advantages. Combat sports can be dangerous. Fairness is what it's all about. We all want fairness in sport."
The Associated Press and Reuters contributed to this report.