Alex Lowes was the fastest rider of the day in opening practice at Assen, despite a tumble for the Samsung Honda rider in the opening session of the day.
He fell in the first practice of the day after leaking oil from a blown engine coated his back tyre, causing him to drop his machine in the gravel traps at turn three. However, he managed to walk away unhurt and the team were able to replace his engine for the second session.
Tyco Suzuki racer PJ Jacobsen was a surprise second in the second practice, finding good form to finish as the highest non-Title Fighter of the day, 0.1 ahead of James Ellison in third.
Lowes' Samsung Honda teammate Ryuichi Kiyonari was fourth, leading the Rapid Solicitors Kawasaki pairing of Shane Byrne and wildcard Nori Haga. Josh Brookes was ninth, after sitting out most of the session then getting caught out by a rain shower.
Tommy Bridewell was tenth on the second Milwaukee Yamaha, struggling both to adopt to the Yamaha machinery after his switch this week from his Halsall Kawasaki, and with a little finger damaged in a crash in free practice one.
James Westmoreland, the final of the six Showdown riders, was 11th, after crashing his Buildbase BMW with five minutes left in the session.
After the session, Lowes told MCN that despite his pace, the team still had work to do.
"We've got a lot of work to do, but it's alright. I really enjoy Assen, and I've having loads of fun out there, so we just need to work on getting some rear grip sorted for tomorrow and we'll be alright; we just need to keep working, like normal on a Friday!"