Olympics day 2: Titmus, O'Callaghan spearhead Aussie swimming heats

The Hockeyroos and Sharks are also in action alongside equestrian cross country, sailors, rowers, skateboarders, women's rugby sevens and more tennis from Roland-Garros. Internationally, the great Simone Biles returns to the gymnastics floor.

Reports emerged on Sunday afternoon that Australia's No.1 ranked men's tennis player Alex de Minaur has pulled out of the Olympic singles draw because of an injury sustained at Wimbledon recently. He will continue in the doubles at Roland-Garros.

Luke Plapp has undergone abdominal surgery following a cycling crash midway through the men's time trial on wet Paris roads overnight (AEST).

Everyone hoped. Everyone dreamt. But no one ever thought this was a day-one reality. Australia is on top of the world after a triple golden treat and double dose of silver on day one of the Paris Olympics.

Grace Brown, Ariarne Titmus and the Australian women's 4x100m relay - or better known as the "untouchables" - won gold medals to kick start the Games in perfect style.

Their results - as well as two more silvers in the pool - mean Australia is on top of the overall medal tally.

The glory will be short-lived given the power of the United States and China, but it was a dream way to wake up on a Sunday morning for Australian sports fans and sets the tone for what many are hoping will be the country's best Games in history in terms of medals won.

Elijah Winnington finished with silver in the men's 400 metres swim. And his mantra summed up how everyone in Australia was feeling after day one.

"Disneyland is one of my favourite places in the world. Everyone is happy in Disneyland. I was lining up for one of my favourite rides and I had to be reminded of my purpose," Winnington said.

Where were you during the Tokyo Olympic Games? Shayna Jack was wandering around a zoo, green with envy while a nation celebrated gold.

A two-year doping ban ultimately cost Jack the chance to compete in Tokyo. Three years later she is an Olympic gold medallist - and an Olympic record holder - after helping Australia to its fourth consecutive triumph in the women's 4x100m freestyle relay.

Jack, Mollie O'Callaghan, Meg Harris and Emma McKeon - whose sixth Olympic gold medal means she now stands alone with more than any Australian in history - are the toast of a nation.

So too is Titmus, triumphant in what was dubbed the race of the century. So too cyclist Brown, who blitzed the competition en route to Australia's first gold of the Games in the women's time trial.

Some turnaround for Jack, who has always maintained her innocence of doping and now turns her attention to the individual 50m and 100m freestyle events.

"I was at Australia Zoo," Jack said as she recalled missing the Tokyo Games.

"I'm a really big animal lover, so is my partner, and I went to Australia Zoo. I still was tempted to watch ... and cheer them on, I love those girls.

"It was joy for them but it was also envy that I couldn't be there. I messaged each one of them after. It was one of those moments that gave me that fight to come back. It actually drove that passion to come back and be part of this team.

"I have so many things I want to achieve this week. I'm going to take that time at the end of the week to reflect but for now it's getting back in the pool, getting ready and striving forward to see what else I can do. This is definitely a great start."

If you were woken by the roars of a housemate or a neighbour this morning, they have no reason to apologise.

It was because Ariarne Titmus raced into the history books, the women's 4x100m relay won their fourth-straight Olympic gold and Grace Brown dominated the time trial.

For Titmus, her race was dubbed the race of the century. The reigning Olympic champion, a seven-time Olympic gold medallist, and a rising star set to challenge the greatest for years to come.

The 23-year-old defended her Olympic crown in the women's 400m freestyle at the Paris Olympic Games at the Paris La Defense Arena on Sunday morning.

Titmus claimed gold in 3:57.49, holding off Canadian Summer McIntosh [3:58.37] and American star Katie Ledecky [4:00.86]. All three have held the world record over this distance in the past three years.

Yet it was Titmus who reigned again, becoming just the second Australian woman after Dawn Fraser to successfully defend her individual Olympic swimming title - history 60 years in the making. Fraser won 100m freestyle gold at the 1956, 1960 and 1964 Olympics.

"I'm just the same old goofy Tassie girl living out her dream," Titmus said. "I hope it goes to show anyone can do what they want to do if they work hard and believe in themselves."

First came Grace Brown, "little old me". To say Brown clinched gold would be an understatement. She blitzed the competition by 91 seconds - yes, that's ninety-one - as everything went to script. Brown became Australia's first ever gold medallist, man or woman, in the discipline.

Paris was going to let nothing rain on its parade. Not even teeming rain. Not even an arson attack on the rail network earlier in the day. The Games of the 28^th Olympiad are officially open.

It was the first opening ceremony in Games history to be held outside a stadium and it was unapologetically French. Aloof, maybe a bit weird, perhaps so clever that most of us didn't understand it.

You had every right to wonder that the burning piano represented as it accompanied a rendition of John Lennon's Imagine. What about the metal horsewoman who galloped along the surface of the Seine? And let's not even start thinking about the "pervy smurf", who was meant to represent the Greek god Dionysus. They should turn him into a limited-edition soft toy mascot.

The entertainment kicked off with a spot by Lady Gaga, metal band Gojira rocked it out singing about revolution, there was opera, DJs, classical and pop. All week there were rumours that Celine Dion would appear, her first performance since she revealed she had a rare progressive neurological disorder.

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By the time she appeared, almost four hours after the first boat full of athletes left port, the opening ceremony was struggling, but under the lights of the Eiffel Tower Dion looked regal and wrapped the whole thing up in such a classy way.

If you were looking for athletes it was a little disappointing. The boats went by pretty quickly, some nations shared a boat, the USA looked like they were aboard a battleship there were so many of them. There was no footage from onboard the boats so the athletes were always at a distance, unlike the ceremonies inside a stadium where cameras weave and bob among the teams.

Opening ceremony uniforms were perhaps a waste of money. We didn't get to see them close up, a lot of them were covered by cheap plastic ponchos once the rain set in. In this sense, it was a bit of a let down.

But was the whole thing a success? It was fabulous to tour through Paris, but really the athletes probably had the best view. From a television perspective it lagged a little, we just felt a little distant from it all.

At one point Australian film director Baz Luhrmann, there in the VIP area with fashion legend Anna Wintour, said the whole night had a certain "je ne sais quoi" about it.

This literally translates as "a quality which cannot be described or named easily."

That's probably an apt way to sum it up.