Marc Marquez wrapped up the second win of his Moto2 career in wet conditions at Assen, and moved up to second in the championship in the process.
Series leader and polesitter Stefan Bradl crashed out near the end of the race, but remains 57 points ahead of Marquez in the standings.
Bradl (Kiefer Kalex) struggled from the outset in the wet race, steadily slipping down the order from pole and falling as low as 13th. He managed to get back up to eighth before sliding out at the chicane in the closing stages.
Simone Corsi, Bradley Smith and Marquez set the early pace, although as conditions improved slightly Corsi would begin to fade, eventually tumbling right back to 14th.
Kenan Sofuoglu then moved up to join Smith and Marquez's lead battle, with Yuki Takahashi shadowing them. All of the first three took turns in front amid some very close racing on the greasy track.
Takahashi picked his way through to second, only to crash on lap 20 of 24. Marquez was leading at that stage, and the accident gave him a little breathing space, as he inched away to win by 2.3sec over Sofuoglu, the Technomag-CIP rider securing his first Moto2 podium. Smith fell back from Sofuoglu as he claimed a second straight top-three finish in third.
Anthony West showed his usual outstanding wet weather form to come through from 21st to fourth on the MZ, a short distance ahead of the battling Alex de Angelis and Mattia Pasini.