Guintoli would keep up the momentum over the coming laps, passing Sykes for fourth on lap six, Haslam for third on lap third on lap nine and Checa for second on lap ten.
Behind him, things remained close, but the lead group would be punctured on lap 13 by a spectacular accident involving Checa and Melandri, the latter having just overtaken the 2011 champion moments earlier.
Caused by Checa out-braking himself into the slow turn four hairpin, the Spaniard attempted to avoid Melandri but would clip the BMW in a heavy impact that would send both barrelling out of the race. Though Melandri was unhurt, Checa has been taken to hospital after reportedly being knocked briefly unconscious in the accident. He will not start the second race.
The incident would serve to break up the lead group, with Guintoli released to begin applying the pressure to team-mate Laverty at the head of the field.
Wasting no time in making his move, Guintoli would simply slipstream past into the first turn on lap 15, nosing into a lead he would retain to the chequered flag.
Eventually winning by just over a second, the victory marks the fourth of Guintoli's career, but the first achieved in completely dry conditions having previously won in the damp at Assen, Silverstone and Magny-Cours.
Behind him, Laverty spent the final laps of his race dicing with Michel Fabrizio
on the Red Devils Roma RSV4, the Italian staging an impressive fight back up the order after a terrible start dropped him from third on the grid to 11th.
Setting the fastest lap as he stealthily charged his way up the order, Fabrizio would get the better of Laverty on lap 20 with a daring move on the run up to Lukey Heights. However, the Irishman would respond at the bottom of the hill on the final lap to sneak second by a mere 0.007secs to claim second place on an all-Aprilia podium.
Behind them, the fight for fourth would be an engaging tussle as Haslam, Sykes, Chaz Davies and Loris Baz disputed 'best of the rest' status.
In the end, Davies would get the better of his rivals, the Welshman defying an average qualifying performance that left him 12th on the grid to scythe his way up to fourth place on his BMW debut.