Australian Emma McKeon set a medal record in the pool and American Xander Schauffele clinched golf gold on a day of hot temperatures and frayed tempers at the Tokyo Olympics.

McKeon became the first female swimmer to win seven medals at a single Games with two golds on Sunday, as a fascinating swimming competition drew to a close hours before the blue riband men's 100m final takes centre stage in the athletics.

In tennis, Germany's Alexander Zverev was in sizzling form as he beat Russian Karen Khachanov in straight sets to take men's singles gold.

American Caeleb Dressel, meanwhile, powered to victory in the men's 50m freestyle and swam an inspired butterfly leg in the men's medley relay to finish with five gold medals.

German world number five Alexander Zverev won the biggest title of his career with victory over Russian Karen Khachanov in the men's singles final.

The 24-year-old became the first German man to win an Olympic singles gold with a 6-3 6-1 win in just 79 minutes.

It was the country's first tennis gold medal as the Czech Republic, having previously won as Czechoslovakia in 1988.

New Zealand's Valerie Adams became the first woman to win medals at four Olympics in a single field event by claiming the bronze, with American Raven Saunders picking up silver.

There are medals up for grabs in the men's high jump and women's triple jump before the 100m.

The individual apparatus finals got under way without American gymnast Simone Biles, who pulled out of Monday's floor final having already withdrawn from Sunday's vault and uneven bar competitions to focus on her mental health.

In the men's floor final, Artem Dolgopyat won Israel's first Olympic gymnastics gold and only their second Olympic title in any sport after Gal Friedman's 2004 windsurfing win in Athens.

American Xander Schauffele clinched the Olympic men's golf gold medal on a nail-biting final day that ended with a seven-way play-off for the bronze medal.