The reigning world champion came off on lap eight as he held third place behind eventual winner Chaz Davies (Aruba.it Ducati) and his Kawasaki team-mate Tom Sykes.
Rea appeared to have a braking or gearbox issue as he slid out of contention while giving chase to Sykes, who has now clawed back more ground in the title race after capitalising on a DNF by Rea in the previous race at Laguna Seca in the USA in July prior to the summer break.
Welsh rider Davies won the race comfortably by more than 10 seconds from Yorkshireman Sykes, with Honda’s Nicky Hayden filling the rostrum places on the Fireblade.
Rea, who qualified sixth fastest on the Ninja ZX-10R, will be aiming to get his championship charge back on track in Sunday’s second race, which is scheduled for a 12 noon start UK time.
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He dominated the title race in 2015 and has been in similar form this season, winning eight races and finishing consistently on the podium.
However, Rea’s back-to-back DNFs have opened the door for 2013 world champion Sykes as the championship adopts a different complexion with Sunday’s second race and three more rounds remaining.