Teenage swim star Mollie O’Callaghan has stormed to victory to take home the women’s 100-metre freestyle gold at the Swimming World Championships in Budapest on Thursday, June 23.

The 18-year-old made phenomenal time, clocking in at 52.62 seconds, only 0.13 seconds ahead of world record holder 28-year-old Sarah Sjostrom of Sweden, making her the youngest winner of the 100-metre freestyle race since 1991.

“I’m so excited, I really don’t know what to say. I wasn’t expecting that at all. I’m racing some amazing girls here,” O’Callaghan said after winning gold at the World Championships.

O’Callaghan had been third in the final 50 of the 100 freestyle semi-final, predicted to finish at a time of 26.42 only to hit the accelerator big time and storm home in the final 10 metres, touching the wall first.

Prior to her thrilling win, O’Callaghan admitted she was suffering badly from pre-race nerves.

“It was bad, the worst ever,” she said.

“I was panicking in my bed, having a little bit of a cramp in my leg, just feeling dizzy, feeling out of it, starting to panic, but I knew I had my teammates there… I guess that kind of uplifted me for the race.

“It’s certainly weird at the moment to think that I’m a world champion.

“I’m so proud of it, it’s all about the experience for me and I wasn’t expecting that at all.”

Her freestyle win marked her second gold medal of the meet after Australia’s 4x100m freestyle relay victory. The young Queenslander now has four medals with her silvers from the 4x200m freestyle relay and individual 200m freestyle.

Overall, it was a golden day for Australia as O’Callaghan wasn’t the only one who snagged a win for the team.

Zac Stubblety-Cook swam an equally extraordinary race and took on the men’s 200-metre breaststroke, earning him the world title.

Stubblety-Cook was last after 100metres before powering through to get himself into third position at the 15 metre mark before blitzing his way through the final length and striking gold.

Their efforts helped bring a smile back to fellow teammate Shayna Jack, who was forced to quit the championships after slipping and breaking her hand in the warm-up area.