Marc Marquez topped the opening MotoGP practice session for the Dutch TT ahead of Maverick Vinales, while Jorge Lorenzo crashed late on.
Championship leader Marquez came straight out of the blocks with a 1:35.359s in the opening stages of FP1, which briefly put him over a second clear of the field.
A 1:35.293s extended his advantage, though Ducati's Andrea Dovizioso cut his lead in the session down to 0.134 seconds, before Pramac's Danilo Petrucci – nursing a broken pinky toe from a crash at the Barcelona test two weeks ago – edged ahead with a 1:35.158s.
Marquez and Petrucci proceeded to trade top spot, with a best of 1:35.037s for Petrucci beaten by almost half a second by the Honda rider.
Yamaha's Vinales leaped up the order to demote Marquez with a 1:34.550s with just under 30 minutes remaining, though Marquez soon returned to the top of the order with a 1:34.411s.
Marquez rasied the benchmark in the closing minutes to a 1:34.227s, which remained as the time to beat as the chequered flag fell.
Vinales slotted into second, 0.117s adrift of his fellow Spaniard, while Yamaha stablemate Valentino Rossi – who took the Japanese marque's last victory in the premier class at Assen one year ago – completed the top three with a 1:34.513s.
Pramac's Jack Miller put on a late charge to secure fourth on his GP17, while factory Ducati man Andrea Dovizioso – who evaluated an updated chassis along with team-mate Lorenzo and Pramac's Danilo Petrucci – was fifth.
Lorenzo was seventh in the end after a fall at Turn 9 in the final minute. Suzuki's Andrea Iannone, running the updated engine test rider Sylvain Guintoli used during the Catalunya weekend, was sixth.
Franco Morbidelli ended the morning eighth on his Marc VDS Honda, 0.009s back from Lorenzo's best and 0.070s ahead of fellow satellite Honda man Cal Crutchlow.
Petrucci rounded out the top 10, while Honda's Dani Pedrosa and Tech3 Yamaha runner Johann Zarco flew under the radar in FP1 in 14th and 13th respectively.
