Prema Racing's Antonio Giovinazzi capitalised on a shocking start for team mate Pierre Gasly to win ihis fifth race of the season n Malaysia.
Gasly dropped well down the order and was easily displaced by his Prema colleague, Sergey Sirotkin, and around half the pack on the run down to the first corner.
The Italian played a long game with strategy and initially looked to have made a mistake, but things came back to him as the race went on, with tyre degradation much more severe than first thought.
Sirotkin opted to pit as early as possible from second place on Lap 7 to swap his softer medium-compound tyres for the harder choice.
Giovinazzi followed suit four laps later, and when he emerged a second behind the Russian, it looked like he and Prema had made a mistake.
However, come the end of the race, Sirotkin ran out of grip, enabling the Italian to catch up to and pass him with a gutsy overtake around the outside of the first two corners.
Further back, one of the hardest-fought positions was fourth place, where British pair Olive Rowland and Alex Lynn squabbled over the first non-podium place. Lynn forced his way through as it was clear that those who stopped very early on – Lynn being one such man – had very little grip left at the end of the race.
This was personified best by Rowland, who after losing fourth, fifth and sixth to Lynn, Rafaelle Marciello and Jordan King respectively, had a huge spin out of seventh place on the last lap of the race, dropping out of the points.
There was no such issue for Giovinazzi though, whose tyres were in great shape at the end of the race, and he finished nearly six seconds head of Sirotkin, with Racing Engineering's Norman Nato third.
Then it was Lynn, King, Marciello and Luca Ghiotto, with Mitch Evans in eighth place taking reverse grid pole. Gustav Malja and Sergio Canamasas rounded out the points, with Gasly finishing point-less in 11th after an uncharacteristically poor afternoon.
Nobuharu Matsishita and Artem Markelov were the only non-finishers, with Markelov grinding to a halt on the formation lap. His Russian Time car took a while to be cleared, and so two additional parade laps were necessary to move the stricken vehicle, reducing the race's distance to 29 laps.
Giovinazzi not taked the lead of the championship from team mate Gasly, going into Sunday's sprint race with an 11-point lead.
