The 21-year-old was leading the 2016 championship when she collided with a photographer during the German leg of the event. She injured her hand and ended up missing the next two rounds.
So when the Palmerston rider took a tumble early in the opening race at Pangkal Pinang, in Indonesia, you could forgive her for having a few doubts.
But there was no time for that, she said.
She just picked up her bike and made her way back through the field on a sodden track to finish fifth.
"I made it quite tough for myself but I had to salvage as many points as I could," Duncan said.
"That race was more like a win to me because I came from so far back and didn’t give up.
"You can’t win a championship in one race but you can lose one. I knew that so it was important I kept charging all the way down to the finish."
Duncan won the second race and left Indonesia with 41 points and on top of the WMX standings, so her tenacity really paid off.
The crash was "just one of those things that can happen" especially in the conditions which were very tough. It poured down and staying upright was half the battle.
"There was no point in stressing out. I just had to get back on the bike and pick off as many riders as I could and not do anything stupid in that situation."
The next event is in Italy next month but Duncan leaves for her training base in Belgium on Monday. She will be based there for the next six months.
Dutch rider Nicky van Wordragen is in second placing on the standings with 40 points. Defending champion Livia Lancelot, four-time champion Kiara Fontanesi and Nancy van der Ven all shape as strong competition as well.
But Duncan’s focus is firmly on her own form and what she can do to get around the various tracks quicker.
"I have to make sure I prepare well and tick all the boxes. I can’t worry about anyone else and just do what I can do."
