World Superbike champion Jonathan Rea claimed the 14th victory of his title-winning campaign, beating Chaz Davies in a thrilling second race at Magny-Cours.
At the start, poleman Leon Haslam headed the field into Turn 1 and withstood a challenge from Rea into Adelaide, with the Kawasaki rider then briefly dropping behind Davies.
But the Ulsterman retook the spot shortly thereafter and was back on Haslam, a late move forcing the Aprilia rider to straightline the chicane and drop to fourth, with Rea himself then passed by Davies.
After a brief battle with Sykes, the champion was back challenging for the lead of the race, catching Davies again on lap 9 and briefly edging ahead before Davies regained the spot down the inside of Adelaide.
But Rea took the lead next time by through the Golf kink and slowly but surely began to edge ahead from Davies and Sykes, the trio now more than four seconds up the road from the rest of the field.
There would be no further fighting in the top three, with Sykes dropping off from the back of Davies and settling for third place.
The result means that Davies and Sykes are now 14 points apart in the battle for the runner-up spot heading into the Qatar finale.
Meanwhile, a charging Michael van der Mark finished as best of the rest, completing a stellar ride from 15th on the grid with a Turn 3 pass on Haslam for fourth place.
Haslam salvaged fifth, ahead of local hero Sylvain Guintoli and front row starter Niccolo Canepa, who equalled his career-best WSBK finish with seventh.
Leon Camier took eighth, with Ducati replacement rider Luca Scassa and Suzuki's Alex Lowes making up the top 10.