Algerian Imane Khelif moved past Angela Carini when the Italian abandoned their welterweight round of 16 fight after 46 seconds in the first round on Thursday.
Khelif has been in the spotlight since she was disqualified just hours before the gold medal match at the 2023 World Championships.
She was ruled eligible, however, to compete in Paris, a competition run by the International Olympic Committee.
Khelif entered the arena amid loud cheers from fans waving Algerian flags and the Italian was no match for her opponent's speed and longer reach.
Carini went to her coach after 30 seconds to fix her headgear but after briefly resuming the fight she returned to her corner and stopped, quickly leaving the ring.
"I have always honored my country with loyalty," Carini said. "This time I didn't succeed because I couldn't fight anymore. So I put an end to the match." She did not immediately say why she had abandoned the contest.
