Making his Olympic debut on Tuesday, the 1500m national record holder controlled his heat from the front before easing off in the final straight to finish third in three minutes 36.39 seconds.

Joining McSweyn in Thursday's semi-finals will be countryman Oliver Hoare, who was third in the fastest of the heats in 3:36.09, with the top six advancing automatically.

The third Australian, Jye Edwards, was narrowly eliminated after finishing seventh in a rough-house opening-round encounter.

McSweyn is rated his nation's best chance of claiming a podium finish on the track at the Tokyo Games.

If he delivers on that promise, the 26-year-old would become the first Australian to claim an Olympic medal in the iconic metric mile since Elliott won gold at the 1960 Rome Games.

"It's been a big build-up and I'm happy with that, I felt good," McSweyn told the Seven Network.

"I went into it ready to run as fast as I could if I needed to.

"The focus is now on the semi."

While McSweyn has been the deserved poster boy for the track and field team in Tokyo due to his record-breaking exploits of the past few years, Hoare has been making a name for himself on the US college circuit.

He transferred that form onto the global stage on Tuesday and is now every chance of joining McSweyn in the Olympic 1500m title race - something only Ryan Gregson in 2016 has done for Australia in the past 45 years.

"(Representing Australia) has been a near and dear thing to my heart," said the 24-year-old Hoare who was in the same year at Sydney's Trinity Grammar with sprint star Rohan Browning.

"It's been hard to sacrifice to move to the US and hopefully that sacrifice is paying off right now."

The hugely-promising Bendere Oboya made no attempt to sugar-coat her performance after being eliminated in the opening round of the women's 400m in 52.37 seconds, well shy of the PB of 51.21 she set at the same stage of her last major event - the 2019 world championships in Doha.

"That was pretty bad," said 21-year-old Oboya.

"But you're going to learn from all these races.

"Not every race is is going to be great and this just wasn't a great one.

"It's not like I was in bad shape or anything.

"I'm not going to be giving any excuses."

Oboya had an interrupted build-up to the Games when she was stuck in Queensland for an extended period of time, away from coach John Quinn and her close-knit training group in Sydney, due to COVID-19 border closures.

Australian Associated Press