Shane Gould is in rare air as one of six Australian swimmers to win three gold medals at a single Olympics.

And she doesn't believe Ariarne Titmus can join the exalted half-dozen by winning Saturday's 800-metres freestyle final at the Tokyo Games.

For the third time, Titmus tackles Katie Ledecky in a freestyle final - but the American megastar is hot favourite for this gold.

"Ariarne's going to have to swim the race of her life to be even on the podium," Gould told Radio 2GB.

"It will be a good race. But she's going to hurt."

While 200m and 400m freestyle champion Titmus is a long-shot, Kaylee McKeown is tipped to deliver her second gold of the Games in the 200m backstroke.

Elsewhere for Australia, with nine gold, two silver and 11 bronze, discus thrower Matthew Denny is well placed to challenge for the nation's first track and field medal in Tokyo after finishing fourth in the qualifying round.

Daniel Stahl is the deserved gold-medal favourite but apart from the big Swede, the event looks wide open.

Denny's best effort of 65.13m in the qualifying round was just one metre shy of his personal best and he is confident of producing something even bigger in the final.

"It's a stacked comp, it's going to be tough," said the 25-year-old Queenslander.

"I'm in really good form when it counts to get the actual distance I need.

"If there's a PB there then sweet and if we go further than that then I'm laughing."

On the track, Rohan Browning will become the first Australian man since Josh Ross in Athens in 2004 to contest an Olympic 100m.

The pace was extremely hot in the opening round of the women's 100m on Friday, raising hopes that Browning could threaten the magical 10-second mark.

Logan Martin, who won his second world title last month, is one of Australian cycling's top Tokyo gold medal hopes as BMX Freestyle makes its Games debut.

Martin and Natalya Diehm will have their seeding round on Saturday morning ahead of Sunday's final.

There are also mixed teams medals up for grabs in several sports, with Australia expected to be at the pointy end of the field in both the triathlon and the trap shooting.

AAP