Sam Bird seals impressive New York double

The DS Virgin Racing driver combined strong pace and a perfect strategy to easily defeat the chasing Mahindras of Nick Heidfeld and Felix Rosenqvist.

Lucas di Grassi finished off the podium again, but another top-five finish means he goes to the final two races in Montreal just 10 points behind championship leader Sebastien Buemi.

Bird started from pole but lost the lead to Rosenqvist on the run to the right-hand Turn 1.

He stayed glued to the Swede's rear bumper, and after a brief full-course yellow interlude thanks to Mitch Evans stopping his Jaguar while running 10th, resumed his attack immediately.

On lap 10 of 49 he lunged Rosenqvist at the tight Turn 6 hairpin, wresting the lead back with a superb and aggressive pass.

From there Bird was faultless, stopping a lap later than the majority of his rivals under another FCY as DS Virgin judged the caution perfectly and gave its driver a lap's extra energy than those chasing him.

That allowed Bird to ease clear when racing resumed, and he won by 11.3s to vault to fourth in the drivers' championship, after starting the weekend eighth in the points.

Heidfeld tried to follow Bird past Rosenqvist when the Briton nicked the lead, and although he failed he shadowed his team-mate throughout.

Red Bull Formula 1 protege Pierre Gasly caught the pair at the end, and the three concertinaed through the final corner - with Gasly throwing his Renault e.dams around the outside of Heidfeld.

Rosenqvist retained second and Heidfeld third, though, as Gasly ran wide, hit the wall on the exit and then on the other side of the track as well as he crossed the line with a crumpled front end.

Fourth was still a superb result for the 2016 GP2 champion, who ensured he beat his much more experienced team-mate Nico Prost in both races on his debut.

More importantly for the man he replaced at Renault, points leader Buemi, Gasly took points off Audi driver di Grassi.

The Brazilian started ninth and worked his way up to fifth, but had no answer to the pace of the leading quartet.

Behind di Grassi, Prost was a distant sixth, and remains without a podium this season, while Tom Dillmann claimed a strong seventh for Venturi, which had lost Maro Engel from sixth early on due to crash damage.

Jean-Eric Vergne was only eighth after Techeetah kept him and team-mate Stephane Sarrazin out a lap too long under the FCY and meant they swapped cars just as the rest of the field resumed racing speed.

Robin Frijns stayed out even later than those two but recovered to a surprise ninth in the BMW-backed Andretti entry, with Jerome d'Ambrosio in 10th.

D'Ambrosio made a forceful move on Faraday Future Dragon Racing team-mate Loic Duval for what turned out to be the final point.

Duval was then punted into a spin a lap later by Antonio Felix da Costa, who dropped to 15th.