Tokyo Olympics 2020: American medal rush begins with a splash

Host Japan follows China in list for most gold medals

Surprise wins and misses dominated the Olympic storyline on Sunday as new champions from unlikely nations joined traditional powerhouses atop medal podiums and stars faltered.

Tunisia's Ahmed Hafnaoui not only stunned swimming superpowers with his gold medal performance in the 400m freestyle — he didn't quite believe the result himself.

The first world record fell in the pool when Australia won the 4x100 women's freestyle relay Olympic gold for the third time in a row. The quartet of sisters Bronte and Cate Campbell, Meg Harris and Emma McKeon took 0.36 seconds off their previous best.

American Chase Kalisz won his country's first gold in the 400m individual medley with a swim of 4:09.42, leading an American one-two with Jay Litherland collecting silver.

Naomi Osaka powered through her opening match

It was a golden day for the host nation, which shared the lead with China for the most gold medals at the conclusion of events on Sunday. 

Swimmer Yui Ohashi held on to beat the Americans in the women's 400m individual medley.

Annemiek Van Vleuten thought she won the women's Olympic road race, only to realise later she had finished second

Judoka Uta Abe triumphed in the women's 52kg category in Tokyo, hours before her brother Hifumi took gold in the men's 66kg final, making history as the first siblings to win gold medals on the same day.

Tunisia's Ahmed Hafnaoui won gold in the 400m freestyle stunning swimming superpowers

Tennis player Kei Nishikori upset fifth seed Andrey Rublev 6-3 6-4 on home soil. Naomi Osaka powered through her opening match.

The US basketball team fell to France 83-76 on Sunday as the Americans suffered their first defeat since 2004 at the Olympics.

The French had upset the U.S. men when they last met in the 2019 FIBA World Cup quarter-finals and they had their number again on the first day of group play at the Saitama Super Arena, powered by a game-high 28 points from Evan Fournier.