Caeleb Dressel and Katie Ledecky added to the United States' gold medal haul at the Tokyo Olympics while Australia's sensational run continued with Kaylee McKeown winning the 200m backstroke for their seventh gold in the pool.

Dressel stormed to the men's 100m butterfly title with a world record time of 49.45 to pick up his second individual gold of the Tokyo Games. He also won gold in the 4x100 freestyle relay.

Ledecky won the 800m freestyle to add to her 1,500 freestyle gold - and also had the satisfaction of defeating her Australian rival Ariarne Titmus for the first time in Tokyo.

Titmus had to settle for a silver medal but there was plenty for Australia to celebrate with McKeown's perfectly timed swim to complete the backstroke double.

World champion Dressel beat Hungary's Kristof Milak, the gold medallist in the 200m fly, by 0.23 seconds.

The powerful American, who also won gold in the 100m freestyle, was fastest out of the blocks and never looked in danger, though Milak came back hard to close the gap down the straight.

Dressel has a busy morning, racing in the 50m freestyle semi-finals and is likely to swim in the final of the mixed medley relay about 30 minutes after that.

Ledecky has been the dominant force in the 800m free and she took control from the outset, increasing her lead over Titmus from the 500m mark.

The American now has six individual career Olympic gold medals, taking her past the record of Hungarian Krisztina Egerszegi who had five.

McKeown turned up the pace on the final lap to power past Kylie Masse after the Canadian held the lead for the first 150.

The Australian won in a time of 2:04.68 with Masse 0.74 behind and McKeown's team mate Emily Seebohm taking the bronze medal.

Australia's women have now picked up six of the country's seven gold medals in the pool.

Meanwhile Great Britain equalled their best swimming medal haul at an Olympics after winning the inaugural mixed 4x100 metres medley relay final in a new world record time at the Tokyo Aquatics Centre.

The quartet of Kathleen Dawson, Adam Peaty, James Guy and Freya Anderson were more than two seconds clear of the rest of the field in the heats, setting a new European record, and Team GB eased to victory on Saturday morning.

Anna Hopkin replaced Anderson for the final freestyle leg here and touched out in three minutes and 37.58 seconds for Britain's fourth gold of Tokyo 2020 and seventh gong overall - matching their tally from London 1908.

The time was 0.83 seconds better than the previous best benchmark of 3mins and 38.41 secs - set by China last year - while they finished 1.28secs clear of China, with Australia taking bronze.