Rea had put himself in a strong position to claim a first WSBK win since the Estoril weekend in May in Sunday morning's race when he sent his Kawasaki up the inside of pole-sitter Alvaro Bautista into Turn 7 on lap 3.
Neither Razgatloglu nor Bautista in third were able to able to challenge Rea for the lead in the next few laps, with the Northern Irishman doing enough to hold on to the lead from the duo.
