Randy Krummenacher (BARDAHL Evan Bros. WorldSSP Yamaha) reasserted himself at Assen after two practice sessions, heading the Friday combined times just a few days after crashing from the leading group at the previous Motorland Aragon round, and then restarting to score points.
Motorland race winner Sandro Cortese (Kallio Racing Yamaha) placed second on a sunny and hot first day in The Netherlands, just 0.034 seconds from the best Friday lap.
Over half a second behind the lead Jules Cluzel (NRT Yamaha) was third. The increasingly competitive Luke Stapleford (Profile Racing Triumph) fourth, and first non-Yamaha rider to enter Superpole 2 automatically.
Another rider on a three-cylinder Supersport bike, Raffaele De Rosa (MV Agusta Reparto Corse by Vamag) was fifth, with Federico Caricasulo (GRT Yamaha Official WorldSSP Team) sixth, riding in temperatures of over 26°C.
Lucas Mahias (GRT Yamaha Official WorldSSP Team) was seventh and the first Kawasaki rider home was Hikari Okubo (Kawasaki Puccetti Racing) in eighth place.
Local rider and ESS part-time competitor Rob Hartog (Team Hartog Against Cancer Kawasaki) finished his opening day ninth, with Niki Tuuli (CIA Landlord Insurance Honda) rounding out his day as top Honda runner in tenth place.
A fast crash in FP1 saw Anthony West (EAB antwest Racing Kawasaki) suffer a right wrist fracture and a concussion, being declared unfit as a result.