Jonathan Rea extended his lead at the top of the World Superbike series to 59 points by winning race one at Assen.
Rea beat English Kawasaki team-mate Tom Sykes by 4.5 seconds, with Italian Marco Melandri third.
Welsh Ducati rider Chaz Davies led for much of the race but retired on the final lap with a technical problem while in second but still vying for victory in the Netherlands.
The triumph was Northern Irishman Rea's sixth win from seven races this season.
The 30-year-old won both races at the Dutch round in each of the last two years, had a win and a third place in 2014, and has enjoyed four further successes since 2008.
Rea will attempt to seal a third consecutive double at Assen when he competes in his 200th World Superbike race on Sunday.
He is aiming to become the first rider to win three consecutive WSB titles.
"Chaz rode very well early on and it was a really fast pace but he made a big mistake and that gave me my chance," said Rea after the race.
"I really enjoy this track and it helps that I've done so many laps in testing and throughout my career. It's a special place for me."
The double world champion had qualified in pole position for the race but was dropped three positions for blocking Davies during the Superpole session on Saturday morning.
Ireland's Eugene Laverty finished eighth on his Milwaukee Aprilia.
|WSB Riders' Championship|
|Jonathan Rea (GB)||Kawasaki||170 pts|
|Tom Sykes (GB)||Kawasaki||111|
|Marco Melandri (Ita)||Ducati||97|
|Chaz Davies (GB)||Ducati||95|
|Alex Lowes (GB)||Yamaha||65|
|Xavi Fores (Spa)||Ducati||57|