Poleman Chilton made a great start to leap into an early lead, having chosen the medium-compound Pirelli tyre, to lead super-soft-shod Davide Valsecchi (DAMS) and Luiz Razia (Arden). Behind them, the Lotus cars suffered contrasting starts: James Calado was slow away, but Esteban Gutierrez charged through from seventh to clip third-placed Razia at the first corner.
Razia held third, but Gutierrez soon relented his fourth place to Calado at Turn 1 on lap three, as the Briton made good use of his softer tyres. Gutierrez was very slow for the next tour, and as Giedo van der Garde sought to find a way past, he left the door open for Johnny Cecotto Jr to sneak past him. Doing likewise behind was Felipe Nasr to demote Jolyon Palmer.
Cecotto ran sixth for half a lap before his car locked up all its tyres into Turn 1 and slammed into the tyrewall, looking suspiciously like a jammed throttle rather than a driver error. He was unhurt, and marshals managed to shift his car and restack the tyrewall without requiring a safety car.
The leaders began to pit on lap 12, with Razia, Calado and van der Garde all pitting together from third, fourth and sixth. Razia and Calado switched their softer tyres for mediums.
Leaders Chilton and Valsecchi pitted to react a lap later, Chilton saving time by only changing his medium-compound rears, whereas Valsecchi changed all four super-softs for four fresh mediums.
Chilton looked into control until he caught the medium-shod cars that were running a very long first stint. As Gutierrez circulated up front until lap 22, Chilton was getting held up by regular backmarker Julian Leal. That allowed Valsecchi to completely erode his earlier advantage, which had been over 2s, with Razia making it a three-way fight for the race win.
Razia made an audacious bid to pass Valsecchi around the outside at Turn 1 on lap 25, with Calado and van der Garde catching the Leal-inspired train too. Leal pitted at the end of lap 25, with the top five now covered by just over a second.
Once in clear air, however, Chilton pulled out 1.4s over Valsecchi in just one lap. But Valsecchi kept him on his toes in the closing stages, poised to pounce if any mistakes were made, getting the gap down to 0.8s, 0.6s and then 0.3s over the last few laps. With one eye on the title, Valsecchi was never going to do anything silly, and settled for second.
He gained five points on Razia as a result, the latter's lead now down to just five. Razia was third, well clear of Calado and van der Garde. Palmer and Nathanael Berthon were sixth and seventh.
The best battle behind the leaders at the end of the race was for eighth, and reversed-grid pole. This became over seventh when Josef Kral's car suddenly slowed with five laps to go, but the man who seemed most likely to get it, Nasr, went off at Turn 1 with just a handful of laps to go.
Erstwhile leader Gutierrez switched to super-softs, but his long first stint hadn't worked for him, and compounded it by locking-up badly as he rejoined.
The Mexican then ran wide with seven laps to go, dropping outside the points, but the attrition in front of him handed him the prized eighth spot, and with it tomorrow's reversed-grid pole.