Bautista started in pole and kept his lead from the off, in conditions so cold that riders were seen warming their hands on their bikes' tyres before the race began.
Reiterberger kept Rea at bay in third with 18 laps to go, as Bautista was left relatively untroubled at the front. Leon Haslam and Alex Lowes took up fifth and sixth position respectively, though the German started to close in. Michael van der Mark took up fourth place.
With 14 laps to go, Rea went into second ahead of Reiterberger, with Buatista ahead by 1.3 seconds towards the end of the lap.
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Lowes waited until lap 11 to take fourth place from Reiterberger, who slipped back but remained on course for his first top-10 finish. Van der Mark started to race up the pack in front of his home crowd.
Haslam and Lowe tussled with four laps remaining as Reiterberger was left well behind in six as he lost stamina, and Haslam edged ahead with two laps left.
Bautista was able to keep clear of Rea as the race drew in, and claimed his 10th race win in the first 10. Van der Mark finished third, and Lowes fourth.
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