The Kawasaki rider finished almost one-second ahead of nearest rival Max Nagl, of
Red Bull KTM, with AXO KTM Silver Action's Jonathan Barragan third.
Teka Suzuki's reigning world champion Steve Ramon took a last minute fourth, while CAS Honda's Billy Mackenzie rounded off the top five ahead of Yamaha Monster Motocross' Josh Coppins.
A superb Clement Desalle was seventh fastest with current world championship leader David Philippaerts eighth as the Yamaha Monster Motocross rider struggled to find his own rhythm.
In the MX2 class, Yamaha Red Bull De Carli's Antonio Cairoli and Red Bull KTM's Tyla Rattray won their respective qualifying heats.
Cairoli battled tooth and nail with Red Bull KTM's Tommy Searle, while Rattray rode a solitary heat up front, eventually finishing five seconds ahead of Molson Kawasaki's Stephen Sword.
