"It was fatigue and just didn't get the snap. You are on the verge of perfect and being extremely average, and that was extremely average."
His attempt to get back into the race was thwarted when two riders crashed heavily in front of him.
"I saw the two riders come together. Luckily they had separated from their bikes and I managed to split between his leg and his bike."
The weekend also proved a success for New Plymouth's Matt Cameron and Victoria Hill.
Cameron not only qualified for his first World Cup supercross but also made it through to the quarter-finals, finishing fourth in his qualifying group behind world champion Joris Daudet. He bowed out in the first quarterfinal won by Willers.
Hill also enjoyed her first venture into international supercross competition, also qualifying fourth in her group before also falling in the quarter-final.
The riders now head to London where they will be joined by Sarah Walker and Kurt Pickard, both back from injury, for three days' practise on the revamped track in London before moving to Birmingham for the world championships.
Results from the BMX supercross World Cup in Papendal, Netherlands today:
Men
Quarterfinal 1: Marc Willers (NZL) 39.047, 1; Sam Willoughby (AUS) 2, Dave Herman (USA) 3.
Semifinal 1: Willoughby 1, Willers 2
Final: Strombergs 1, Willoughby 2, Herman 3. Also: Willers 5.
Women
Quarterfinal 1: Caroline Buchanan (AUS) 1, Laetitia Le Corguille (FRA) 2, Magalie Pottier (FRA) 3. Also: Victoria Hill (NZL) 7.
APNZ ks lb