The teenager, who only turned 15 earlier this month, clocked a sizzling 31.34 seconds to win gold in the 50m open-age breaststroke at the NSW Open Championships in Sydney last weekend.

However, at Olympic level, there is no 50m event.

Still, no Australian female at either 14 or 15 years has ever completed a quicker lap in the discipline.

Toohey backed up the win in Sydney with a sliver medal in the 100m breaststroke, just 0.14 secs behind Olympian Jenna Strauch.

The Tokyo Olympian turns 27 on Sunday, highlighting her rival's rapid development.

In fact, in a sport where improvement is often measured in tenths of a second, Toohey has bettered her personal best over 100m in her last three swims.

"They've got her in their sights," Albury Swim Coach Wayne Gould replied when quizzed if the teenager could make the Australian team for Paris, without naturally giving too much away, given there's still three months until the selection trials.

Toohey has a personal best of 1:07:98 for 100m and the Australian Olympic qualification standard is 1:06:31, with the Australian set standard at 1:06:80.

It means if the Albury High School year nine student wins the 100m at the Olympic trials in June, she will compete in Paris.

The runner-up's time will dictate whether they are also selected.

"Anything's possible," the youngster replied when asked if she believes she can win Olympic selection.

As well as churning out 30-40kms a week in training over eight sessions a week at Albury, along with two gym sessions, Toohey also travels to the Australian Institute of Sport in Canberra to train under four-time Olympic coach Shannon Rollason.

The ACT Performance Centre head coach has mentored Olympic gold medallists Jodie Henry and Alice Mills.

"He's taught me a lot of little technique issues, like my turn is definitely one of them and other little aspects that have made a whole lot of difference," she praised.

Rollason also works with Gould, who is delighted with the progress of not only one of his star performers, but the club overall.

"Look, it's a great culture there at the moment, Sienna has come up through the ranks and she always stood out through the juniors, she's had some terrific coaches there and the coaches at Albury I reckon are the best in the business," he enthused.

"They present the kids to me at 12 and they're perfect, all I've got to do basically is get them fit.

"The whole support crew, assistant coaches, strength coach, mums and dads, the committee, everything is a buzz because everything's working, it's infectious when you have a couple of swimmers getting results at the top end.

"We have eight national swimmers and they're supporting each other."

Team-mate Isabelle Rae, who combined with Toohey to win six medals at last year's Australian Age Championships on the Gold Coast, is another in the national firing line.

"They are extremely talented kids and work extremely hard, if you put that formula together, working hard and talented, the end result is a champion," Gould explained.

"They (Swimming Australia) are looking at both kids for the Pan Pacs (Junior Pan Pacific Swimming Championships) in August, straight after the Olympics, so it's a busy time over the coming months."