WFR Honda's Alex Lowes turned the screw to end the opening day at Assen on top of the pile as reigning champion Tommy Hill crashed in FP2.
Hill escaped unhurt after he went down on his Swan Yamaha at Turn 7, slipping to ninth place in the session as Lowes took the top spot with a sizzling 1m 37.893s lap.
Lowes, who has prior experience of competing at Assen after he tested with the Castrol Honda World Superbike team at the iconic venue last year, battled with Tyco Suzuki's Josh Brookes for the honour of heading the leaderboard overnight at Assen, with the Aussie finishing second fastest with a time of 1m 38.175s
Rapid Solicitors Kawasaki ace Shane Byrne, who topped this morning's opening free practice session despite carrying a shoulder injury, continued to show strong form on the ZX-10R as he secured third position ahead of the much-improved Showdown rival Michael Laverty on the Samsung Honda, who was down in 13th place after FP1.
Byrne is almost six tenths adrift of Lowes, with Laverty a further three-tenths in arrears.
Former World Superbike protagonist Jakub Smrz continues to impress on his debut on the Splitlath Aprilia RSV4 as he moved up the order to fifth ahead of Buildbase BMW's pair Barry Burrell and Patric Muff on the Supersonic BMW S1000RR.
Luca Scassa was the best of Clive Padgett's riders in eighth ahead of Hill and veteran Chris Walker, who rounded out the first ten, some 1.4s off Lowes' time.
Jon Kirkham on the second Samsung Honda was next followed by Showdown contender Tommy Bridewell and Ian Lowry, who also crashed without injury in FP2.
There was more misery for Alastair Seeley on the Tyco Suzuki who could only manage 18th ahead of Robbin Harms and Noriyuki Haga, who plummeted down the order to 20th after posting the sixth quickest time in FP1.
Haga developed a technical issue with his Swan Yamaha which forced him to miss the second half of FP2.
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