Duncan steadily rose through the junior ranks, winning titles locally, nationally and internationally and beating the boys along the way. However, in a career reminiscent of Prumm's, Duncan was also prone to pushing the envelope. Inevitably, this also led to her crashing heavily and requiring some heavy surgery.
Surprisingly, her most recent accident came from falling off a Swiss ball during training, tearing the anterior cruciate ligament (ACL) in her knee. Duncan is well into her rehab and is keen to kickstart her racing career again under the guidance of Yamaha New Zealand's team manager, Josh Coppins.
"I remember those world championship races. I was only a little 13-year-old and racing against some boys who were 15," said Duncan. "It was my first international race. I didn't feel any pressure and just went out there and raced.
"I used to watch Josh Coppins, Ben Townley and Katherine Prumm on TV and thought I could do this as a job. The turning point was those world champs when I finished sixth and I thought I could ... be a world champion.
"That was six years ago and I haven't really made it yet as we've had a few ups and downs along the way including quite a few injuries."
Duncan has damaged her knees, wrists, ribs and suffered a couple of concussions although these setbacks haven't stopped her from racing and winning in Australia and America.
Well on the way to recovering from her latest surgery, the 18-year-old from Otago is looking forward to racing again.
"I'm working alongside Josh Coppins and he's the best guy out there to be mentoring and coaching me to get back to Europe and win a world championship," said Duncan.
Coppins, who has had an illustrious international motocross career himself, is very pleased to have the undoubtedly talented Duncan under his wing and is keen to temper her huge talent and speed with a little more nous to keep her on the bike.
"Courtney is very talented and very quick but is prone to pushing it too hard and too far.
"A lot of the stuff we're working on is managing her day-to-day performance, her whole race day and curb her hell-for-leather approach.
"She has an abundance of drive, talent, passion, desire and skill. It's a matter of explaining progression and when to push and when not to push," Coppins said.
"I'm looking forward to working with Courtney and with the right structure around her we will do some great things."