Czech duo Katerina Siniakova and Tomas Machac won the Olympic Games tennis mixed doubles gold on Friday but opted to keep their private life under wraps.

Siniakova and Machac triumphed 6-2, 5-7, 10-8 over China's Wang Xinyu and Zhang Zhizhen.

They started dating in 2020 but recently were rumoured to have split.

"That's our personal life so you don't need to know that," said 29-year-old Siniakova.

Machac added: "This is top secret. In red letters, top secret."

Victory for Siniakova was her second Olympic gold after she and Barbora Krejcikova won the women's doubles title in Tokyo three years ago.

She also has nine Grand Slam doubles titles, two of which came in 2024 with Coco Gauff at the French Open and Taylor Townsend at Wimbledon.

"I think it definitely helps to have that experience. Because in doubles, especially, you play those super tiebreaks a lot," she said.

Machac said victory was bittersweet as it came against Zhang, one of his closest friends on tour.

"I feel really sad for him, because I know how he likes to represent his country, and to bring the gold medal," said Machac.

"He always said that it was his life goal to achieve any medal for the country. I'm really sad about it, but on the opposite, I'm also happy to receive the gold medal. I wish him all the best, I really like him as a person."

Wang and Zhang were attempting to win only China's second tennis gold medal after Li Ting and Sun Tiantian in women's doubles at Athens in 2004.

"Our friendship is totally broken. He destroyed my Olympic Games… everything. This is a joke. We have a really good relationship," said Zhang of Machac.

China can still win tennis gold when Zheng Qinwen faces Donna Vekic in the women's singles final on Saturday.