One of the two boxers who have sparked a gender eligibility row won again at the Paris Olympics on Wednesday to ensure she has a shot at a gold medal.

Taiwanese fighter Lin Yu-ting called it "a tough journey" after claiming a unanimous points decision victory over Esra Yildiz Kahraman of Turkey at 57kg in her semi-final.

That win came 24 hours after Algeria's Imane Khelif reached her final.

After the decision came through, the Turk made an X sign with her fingers, just as another of Lin's beaten opponents had done in a previous bout. 

Kahraman refused 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 are competing in Paris despite being disqualified from the world championships last year by the International Boxing Association (IBA) after reportedly failing gender eligibility tests.

On the track, American sprinter Quincy Hall lunged at the line to win a gripping men's 400 metres.

Hall became the fourth fastest one-lap runner in history when he denied Britain's Matthew Hudson-Smith gold in a time of 43.40sec.

It ended a 16-year drought for the USA in the event. Zambia's Muzala Samukonga took bronze.

"I don't give up," said Hall. "I just got grit. I grind. I got determination.

"Anything that I can think of, that's what gets me to that line. I think of all the hurt, all the pain."

Noah Lyles put himself in a position to go for an Olympic sprint double on Thursday, looking comfortable in finishing second in his semi-final behind Botswana's Letsile Tebogo.

Lyles, who won the closest 100m final in modern Olympic history by just five thousandths of a second on Sunday, will be hot favorite to become the first man since Usain Bolt at the 2016 Rio Olympics to achieve the 100m-200m double.

In other athletics action in the Stade de France Morocco's Soufiane El Bakkali joined an elite group of Arab double gold winners by taking his second consecutive 3,000m steeplechase title.

Only his Moroccan compatriot Hicham El Guerrouj, who won 1500m and 5,000m gold at Athens 2004, and Tunisian swimmer Oussama Mellouli (1500m freestyle in Beijing 2008 and 10km marathon in London 2012) have achieved the feat.

Jamaica's Roje Stona achieved an upset men's discus win and Nina Kennedy took Australia's first ever pole vault Olympic title.

Australian skateboarding gold

Keegan Palmer of Australia won his second consecutive Olympic men's park skateboard title with some spectacular moves.

American rapper Snoop Dogg was among the fans at the Place de la Concorde venue to see if Palmer could retain the title he won when skateboarding made its Olympic debut in Tokyo three years ago.

The US-born 21-year-old did not disappoint, leading from start to finish. American Tom Schaar won silver and Brazil's Augusto Akio bronze.

Keegan said his goal was to skate on to the 2032 Brisbane Olympics -- providing he can keep his younger rivals at bay. "Definitely the goal is to do Brisbane because it's where I grew up, it's where I learned to skate," he said.

"But you've just got to keep up with these kids coming through because skateboarding is a young generation sport."

French golf delight

At Golf National, home favorite Celine Boutier delighted the crowds as she cruised into a three-shot lead after the opening round of the women's golf event.

Boutier poured in eight birdies in a brilliant seven-under-par round of 65.

South Africa's Ashleigh Buhai is second, while reigning champion Nelly Korda battled back from a poor opening stretch of holes to finish on even par, seven strokes behind Boutier.

The first gold of the weightlifting programe went to Li Fabin, who retained his Olympic 61-kilogramme title.

In track cycling, Australia ended a 20-year wait to claim the Olympic men's team pursuit gold medal while the road race champion from these Games, Kristen Faulkner, helped power the United States to the women's title.

On another lightning quick day at the velodrome, Dutch star Harrie Lavreysen shattered the men's sprint world record, stopping the clock at 9.088sec.

Host nation France were eliminated in men's handball, an event they had hoped would produce a gold medal, when the reigning champions lost 35-34 to Germany.

In other developments, Australian Olympic field hockey player Tom Craig was arrested on suspicion of buying cocaine from a dealer in Paris. His team said he was later released with a warning from a French judge.

In the medals table, the USA moved onto 27 golds, two ahead of China while Australia moved into third place with 18 golds.

Source: AFP, by Guy Jackson