Lani Pallister has made the most of the absence of world champion Li Bingjie to win Australia's first gold medal of the world short course championships in Melbourne.
World record holder Li was a shock absentee on the opening day of racing with Chinese media reporting she had a fever.
Australian star Ariarne Titmus, who Li took the record from, also skipped the meet.
The daughter of former Australian distance swimming great Janelle Elford, Pallister qualified second fastest into the 400m freestyle final behind Kiwi Erica Fairweather.
But Pallister turned the tables in the final, powering home in three minutes 55.04 seconds.
A former world junior champion, the 20-year-old has had a horror run with injury and illness over the past 18 months, undergoing heart surgery as well as battling an eating disorder and glandular fever.
She wasn't thrilled with her time but was delighted to have won gold with her mum in the stands after almost giving the sport away.
"I pretty much gave this sport away at the end of last year - I hadn't trained for close to three months and didn't really want anything to do with it anymore," Pallister told reporters.
"It was more that I lost my love for the sport as I'd missed four senior teams in a row by one spot, which when you're that close constantly, it's just kind of like breaks your heart one by one.
"So to be in the position that I am at the moment ... now competing here at short course with a gold medal is just insane."
Pallister won a bronze medal in the 1500m at this year's world championships and finished fourth in the 400m, while she won Commonwealth Games bronze in the 800m.
She swept the pool at the national short course championships, winning the 400m, 800m and 1500m.
Pallister will contest all three events this week and has high hopes.
"As much as I'm not 100 per cent happy with the time I am excited to jump into the 1500 and 800 as I've been doing a lot more distance work than speed work in the pool," she said.
