Horton faced fears to make a Rio splash

Once scared of water, Australia's Mack Horton is now swimming's man without fear.

Aged nine, a shy Horton got his mum to ask idol Grant Hackett to pose for a picture at the 2006 Melbourne Commonwealth Games.

It inspired him to swim for Australia.

There was just one problem.

He dreaded the pool.

Most fearful kids would baulk at dipping their toe in the water.

But Horton addressed the problem by diving in head first.

He took swimming lessons.

Horton hasn't avoided a challenge since.

It led to him making another splash - this time at the Rio Olympics.

The 20-year-old celebrated his 400m freestyle victory over China's controversial Sun Yang as a "win for the good guys".

Dual London Olympic gold medallist Yang served a three-month ban for testing positive to banned stimulant trimetazidine in 2014.

Horton dismissed Yang as a "drug cheat", vowed to take a stand against doping in sport, and hoped to inspire others to speak out.

Quite a memorable Olympic debut, then.

Certainly it has been worth the wait for Horton.

Four years ago Horton was devastated when he narrowly missed London Olympic selection in his specialist event, the 1500m freestyle.

When he made his international debut at the 2015 world titles in Russia, there was only more disappointment.

Tipped to threaten Yang in the 400m and 1500m, he failed to even make the finals in either event.

It later emerged he had been struck down by a gastro bug and lost 5kg in two days before competing.

Somehow he willed himself to 800m freestyle bronze in Russia.

"In Kazan he learned about the journey," Australian head coach Jacco Verhaeren said.

"For some reason it had to happen there.

"Winning here started when he lost in Kazan."

Horton never did lose sight of his Olympic goal - even with poor vision.

A short-sighted Horton needs thick prescription goggles to compete.

He needs a teammate to provide him his spectacles for post-race media, otherwise things could get ugly.

"I can barely see my hand in front of my face," Horton laughed.

Still, Horton has a bold vision - to be the nation's greatest 400m and 1500m freestyle swimmer.

That will involve striking off some of the sport's most revered names - his idol Hackett, Ian Thorpe and Kieren Perkins - from the record books.

His personal best effort (three minutes, 41.55 seconds) that claimed Rio gold placed him just behind Thorpe on Australia's 400m all-time list.

Horton trails only his hero Hackett in the 1500m all-time standings.

Not that he needs to be reminded.

Since he was a kid he would study through his thick-rimmed glasses a list of the top 1500m times he had written on his bedroom wall, dreaming of the day he could slot among them.

He has Australian swimming's greats in his sights.

But first he must again stare down Sun at Rio - this time in Saturday's 1500m freestyle final at Rio.

Once again, Horton has vowed to face the challenge head on.

"To win at an international meet like this you have to be confident," Horton said.

"Anyone in the pool can win, it's just who believes they can do it the most - I believe I can do it the most."