A day after Algeria's Imane Khelif reached the 66kg women's gold-medal match, Lin claimed a unanimous points decision victory over Esra Yildiz Kahraman at 57kg in her semi-final. After the decision came through, the Turk made an X sign with her fingers to the crowd, just like another of Lin's beaten opponents had in a previous bout. Kahraman declined to say afterwards what it meant.

In most cases, males have both an X and Y chromosome, while females have two X chromosomes.

Lin and Khelif both fought at the Tokyo Olympics three years ago but there was no controversy at the time and neither won a medal. Both were disqualified from last year's world championships after failing gender eligibility tests, but were cleared to compete in Paris.

"The feeling of entering the gold-medal match is one of gratitude to myself for making it this far," said the 28-year-old Lin. "After going out in the first round of the Tokyo Olympics, it's been a tough journey to reach the finals."

A former two-time world champion, Lin was given a warm reception as she entered the arena at Roland Garros, usually home to Grand Slam tennis but hosting the closing stages of the Olympic boxing. The top-seeded Taiwanese enjoyed a clear height advantage over the more compact Kahraman and used her reach to pick off her Turkish opponent, who tried to make it a close-quarters brawl.

Having won the first round, Lin snapped Kahraman's head back early in the second round, to oohs from the 15,000-capacity Court Philippe-Chatrier. Oohs turned to boos when Lin hit the back of the Turk's head.

With two rounds in the bag, Lin just had to avoid serious trouble in the third, and she did that, the two fighters greeting each other at the bell and again as the Taiwanese exited the ring. Lin also bowed to three sides of the stadium, to cheers and applause from the crowd.

She faces Poland's Julia Szeremeta on Saturday for gold following her third victory in the French capital. By reaching the title decider Lin is assured of at least silver.

Legal threat

The gender furore ignited when Khelif defeated Angela Carini in 46 seconds in her opening bout in the French capital, the Italian reduced to tears and abandoning the fight after suffering a badly hurt nose. The 2023 world championships Lin and Khelif were expelled from was run by the International Boxing Association (IBA) but the International Olympic Committee (IOC) is organising the sport at the Games because of financial, governance and ethical concerns at the IBA.

The IBA's Kremlin-linked president Umar Kremlev claimed at a chaotic press conference on Monday that both fighters had "genetic testing that shows that these are men".

The IOC has leapt to the defence of Khelif and Lin, with President Thomas Bach saying they were born and raised as women, and have passports saying that. Neither boxer is known to identify as transgender.

Both fighters have been strongly backed by authorities back home and top Taiwanese sports officials have threatened to take legal action against the IBA following Monday's press conference.

Khelif fights China's Yang Liu in the 66kg class on Friday for gold.