RIO DE JANEIRO • They bristled whenever they were asked about 2012 - of their poor harvest in the pool and appalling behaviour outside it.

So when the Australian swim team began the Rio Olympics competition with two golds on Day 1 - already surpassing their gold harvest at the London Games - they could not help but feel a sense of relief at their efforts to erase that huge black mark.

Fittingly, their women's 4x100m freestyle team underscored their brilliance by retaining their title in world-record time.

Powered by sisters Bronte and Cate Campbell, as well as Emma McKeon and Brittany Elmslie, they defeated the United States and Canada in 3min 30.65sec, beating the previous world mark of 3:30.98 they set in Glasgow in 2014.

"Definitely my favourite race ever - in an Olympic final with my sister and two girls I have known since I was 12, 13 years old - and a gold and a world record. Everyone is just pulling together," Cate told the Sydney Morning Herald.

"We've got a great team, a great support team and we've got a great vibe going and hopefully this will kick the momentum off and we'll get the ball rolling with this."

Four years back, the relay win was all that the Australians had in the pool - the first time since 1976 that they did not win any individual swimming gold medal.

Worse still, a post-Games review then found that a "toxic culture" had developed in the team, along with evidence of drunkenness, prescription drug abuse and mismanagement by senior staff.

Since then, they have insisted that they have moved on - Cate Campbell has labelled the constant questions surrounding the 2012 debacle "disrespectful" - and, on Saturday, they gave their most convincing riposte when Mack Horton clinched the 400m freestyle gold in 3:41.55, edging out defending champion Sun Yang by 0.13sec.

"It hasn't really sunk in yet," said the 20-year-old Australian, who is also competing in the 1,500m free.

"I have a couple more races this week, so I need to relax a little bit and focus on those, but it's very exciting."

However, while the Australians are finding their winning form in the pool, they remained controversial off it, as Horton sparked a war of words with Sun.

Asked for his thoughts on doping violators Sun and South Korean Park Tae Hwan competing at the Games, Horton sniffed: "I don't have time or respect for drug cheats."

That prompted an outcry from Chinese journalists, who demanded to know why he had used such frank language.

"I used the word 'drug cheat' because he tested positive," replied Horton. "It's not a question about me and Sun. I just have a problem with athletes who've tested positive and are still competing."

Sun, who had burst into tears when talking to Chinese reporters immediately after the race, insisted he had nothing to hide.

"I'm clean," he growled. "I've done everything it takes to prove I'm clean. I don't owe any more explanations. All countries have their own internal affairs and all athletes deserve respect."

For now, though, what the Australian team must do is to manage expectations - with the most ambitious of estimates forecasting Australia's haul of gold to run into double figures over the next week and surpass the record of eight from the 1956 Melbourne Games.

REUTERS, AGENCE FRANCE-PRESSE