Australian Emma McKeon has become Australia’s second double gold medallist at the Tokyo Olympics, blazing the 100-metre women’s freestyle on Friday.

The 27-year-old led from start to finish: She was first off the blocks in a reaction time a tenth of a second quicker than any rival.

Fellow Australian Cate Campbell was right on her heels in the first lap, but McKeon was too strong,  harnessing that momentum and splashing her way to a glorious gold medal as Campbell took bronze.

McKeon told the Seven Network her week at the Olympics has been an emotional rollercoaster.

“I can’t believe it,” McKeon said.

“Honestly, my emotions are a bit all over the place right now. I know all of my family back home are watching and I felt them with me in my race.

“I know all the support they’ve given me over all the years of me swimming. They’re part of it all.”

The dual-gold-medallist said she owes much of her confidence to her coach Michael Bohl.

“He’s just put so much hard work in and I honestly wouldn’t be here without him,” she said.

“He’s coached some incredible athletes and for him to have the belief in me that he has, I would be stupid to not have the same belief.”

McKeon won Friday’s 100-metre final in an Olympic record-breaking 51.96 seconds followed by Siobhan Haughey (52.27) from Hong Kong and Campbell (52.52).

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She’s become the first Australian athlete to win four medals at Tokyo and is threatening the Australian record for most medals at a single Olympic Games.

McKeon entered Friday’s 100-metre freestyle final as the hot favourite to win her fourth medal of the Games and she has pulled off the incredible feat.

Already with gold from the 4×100-metre freestyle relay and bronzes in the 100-metre butterfly and 4×200-metre freestyle relay, McKeon was the quickest into the 100 free final.

Her long-time teammate Campbell was third quickest in the qualifier and was also swimming to match countrywoman Ariarne Titmus as a dual gold medallist, but just didn’t quite crack it.

Campbell did achieve bronze though, a huge accomplishment, and was full of pride for her teammate.

“This is my fourth Olympics, but this is only my second individual medal,” Campbell said.

“It honestly means the world to me. I’m so happy for Emma.”

McKeon is likely to feature when Australia contends for a 4×100-metre mixed medley medal, which could give her a record sixth medal of the Games.

Swim legends Gould and Thorpe hold the Australian record for the most medals at one Games with five each.

In other action as Australia seeks to add to its nine gold, two silver and 11 bronze medals, Lucien Delfour is a big chance in the men’s K1 canoe on Friday afternoon,

He qualified third-fastest for the semi-finals, with the medal race to follow.

A win from Delfour would make a pair for Australia in the canoe slalom, with favourite Jess Fox bringing home a glorious gold in the women’s C1 on Thursday night.

Slow row for Australia

Earlier on Friday, Australia’s rowing team failed to deliver a similar result to their glittering gold efforts on Wednesday.

Australia’s women’s coxed eight have finished in fifth place, with Canada taking gold for the first time in almost 30 years.

Maintaining fourth place with 150 metres to go and pushing for bronze, they just didn’t quite get the push they needed.

Australia have never won an Olympic medal in the women’s event and were in the hunt at the halfway mark only to be edged out by their rivals.

Minutes later, Australia’s men’s coxed eight were unable to overcome a slow start and finished dead last, with New Zealand the shock winners.

The disappointing outcomes follow a stellar day for Australia’s rowing team on Wednesday.

Within hours, the Aussies had won gold in the men’s and women’s coxless fours, plus added two bronze medals in the men’s and women’s quad sculls.

Elsewhere on Friday, the highly anticipated BMX racing semi-finals, featuring Australians Lauren Reynolds and favourite Saya Sakakibara, has been delayed due to weather conditions.

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Australia is chasing another medal on Friday night, with Pat Tiernan hitting the track and running for gold in the 10,000-metre final.

-with AAP