Emma McKeon sets Australian record at Tokyo Olympics

The Illawarra talent finished equal first in her heat of the 100 metres butterfly alongside China's Yufei Zhang.

Read more: Matildas fall to Sweden in eventful Olympics clash

The time of 55.82 seconds was quick, 0.11 of a second quicker than McKeon swam at the Australian trials and in a positive sign, the 27-year-old is confident she can go even faster in the semi-final and final.

"I'm pretty happy with that," McKeon told Channel 7. "I didn't really feel like I was going that quick. That gives me a lot of confidence going into tomorrow morning."

The event was the first of seven for the swimmer, the talent looking to surpass the great Ian Thorpe in Australia's record books in Tokyo.

McKeon and Zhang were the fastest qualifiers for Monday morning's semi-finals, with defending champion Sarah Sjstrm third after taking out her heat in a time of 56.18.

The Swedish veteran edged American youngster Torri Huske while Canada's Margaret MacNeil comfortably won the third heat in 56.55.

Australia's Brianna Throssell scraped into the semi-finals in 16^th place.

While McKeon is the equal top seed, she knows heat swims count for nothing once the semi-finals commence.

"I knew the Chinese girl next to me would be fast, because I saw her go quick at the end of last year.

"You don't really know what anyone's going to do here because I feel like everyone is on an even playing field once you get to the semis and finals, so I'm just excited to be here."

McKeon will also contest the 4x100m freestyle relay final on Sunday after the Australian team won their heat.

The Wollongong talent and Cate Campbell sat out Saturday's heat as their teammates ensured the squad is safely through to the medal race as the fastest qualifiers.