One of the enduring images of Tokyo 2020 will be the sight of Dean Boxall's exuberant celebrations after Ariane Titmus won an epic women's 400 metres freestyle race.

It was the sheer joy and exuberance on the face of the rock-star looking coach as he wildly revelled in the momentous achievement of his pupil, who had just toppled the great Katie Ledecky in the most sensational fashion.

"I can't help it. I bleed with my athletes. When they leave the pool deck with me – whether I'm having a chat with them for an hour if it has to be – but when they leave, they have to start the recovery process and go home. They switch off. I don't. I go home and dream for them. I go home and try and find a way for them to get better," Boxall explained after he had gone viral on social media.

Titmus herself saw the funny side.

"That's just the way Dean is," she said. "He's very passionate about what he does – he really becomes quite animated.

"This is just as much for him as it is for me. He has sacrificed a lot in his family life, his kids and his wife, for his job. He puts 100 per cent into being a swimming coach. I would not be here without him."

But it was something else Boxall said that really went furthest to explaining his emotional display.

"I've been with her for five years. Having a dream together. Katie was so far in front of us that in the beginning when I started to coach her I couldn't even have this conversation," he said.

"When Arnie came to me she was a 4.12 [in the 400m]. At that stage Katie went 3.56. That's 16 seconds. We just started chipping away, we started to believe."

From a dream, to belief, to the reality of being an Olympic champion.

On Wednesday, Titmus would confirm her status as a breakout star of Tokyo 2020 with another victory in the 200m free filled with fight, desire and a never-say-die attitude.

Billed as Titmus versus Ledecky II, there was a sense of deja vu about Litmus' performance but another battle with her equally brilliant rival – now a six-time gold medallist over three Games after winning the first ever Olympics women's 1500m race – failed to transpire as the American could only finish fifth.

Instead it was Hong Kong's Siobhan Haughey who brought the very best out of Titmus. It took a huge effort down the final 50m to break the Olympics record in a time of 1:53.50.

At the medal ceremony there were tears and a warm embrace with Boxall, the emotion spilling out of this cool customer after becoming just the third Australian, along with Shane Gould and Ian Thorpe, to complete a 200 and 400m free double at a single Olympics.

"I feel like I'm pretty good at containing my emotion I knew that's something I had to do after the 400 because the 200 was right after," Titmus told a news conference after doubling up.

"Now that I haven't got a swim tonight I think I kind of let it out a bit, seeing him [Boxall] and seeing him emotional makes me emotional because this is a great partnership, this isn't just me winning, this is him winning so I think that's why I got so emotional."

For the uninitiated, this week is not the first time Titmus has triumphed over Ledecky, the 20-year-old from Tasmania having taken out the gold at the 2019 World Championships in Gwangju.

But Ledecky, who had won the 200 and 400m free at Rio in 2016, had been contending at that meet with a stomach virus and prior to this week it was far from certain where the golds were headed.

Titmus has emphatically answered the question, though, and it is her personable qualities that have made her resonate this week.

So too have the ferocity, tenacity and sheer awesome speed of her performances.

The Aquatics Centre, as Titmus herself adhered to when addressing the media, provides about as close to a normal experience as you're likely to find at Tokyo 2020. While there are still swathes of empty seats in this 15,000 capacity venue, there are areas designated to team-mates and coaches – all cheering, chanting and applauding to create at least some semblance of an Olympics atmosphere. 

But it is Litmus' displays that have brought true electricity, not only to the pool but for the Games at large.

Two more chances at gold lie in wait in the 800m (where Ledecky, a gifted long-distance swimmer, is favourite) and the 4x200m freestyle relay.

Regardless of what happens in those races, a new star has been born.