The Otago rider had to settle for fourth place after a crash resulted in her slipping back from first in the opening race on Sunday.
But the tenacious 20-year-old gritted her teeth and rode through pain to win her next race by a comfortable margin. Experienced French rider and 2008 world champion Livia Lancelot could not stick with the Palmerston flyer and finished 25sec behind her.
Local hope Nancy van de Ven was more than a minute behind in third place.
Van de Ven won the first race and claimed the series win. But Duncan's win and fourth placing was good enough for second and she leads the overall women's motocross world championship standings after two events with 93 points.
Duncan is in her rookie season on the circuit and took the sport by storm in winning both events in the opening leg of the championship in Qatar. She has three wins from four races in the championship and appears unstoppable when she can stay on her bike.
After her spell in the opening race in the Netherlands, her Yamaha needed some serious work. The handle bars were crooked, the suspension was broken and her front brakes were not working.
It was remarkable she was able to finish, let alone hold on to fourth place and nearly pip the third place rider.
‘‘When you watch that first race her suspension was pretty average,'' her mother, Linda Duncan, said.
‘‘But she looked sweet as last night. No errors. She got out second and I think she was in the lead by the first lap and stayed there.''
‘‘She is still hurting and is pretty sore from the crash the day before. She is pretty tough but she said she was a bit sore.
‘‘She'll be gutted she didn't get the clean sweep but she is still leading [the championship], so that's good.''
The next round of races is in Germany in May but Duncan has a few engagements before that.
First up is an appearance on long-running children's television show What Now this weekend.
Following that, she will attend a training camp with Josh Coppins and then head back to Europe for the remaining events.
