Antonio Giovinazzi completed a remarkable double as he won the GP2 sprint race in Baku ahead of Prema team-mate Pierre Gasly.
Giovinazzi tumbled down the order in the early stages from eighth on the partially-reversed grid, but recovered to win a race blighted by chaotic safety car restarts.
The start itself was incident-free, Nobuharu Matsushita leaping off the line from third and diving down the inside of Daniel de Jong to seize the lead at Turn 1.
The ART driver then scampered clear into an early 2.1-second lead before the safety car was called on lap eight when a collision between Jordan King and Jimmy Eriksson over ninth left the Arden car in the barriers.
Matsushita went too soon at the restart and was forced to slow on the pits straight to avoid passing the safety car, which was still making its way into the pits.
Oliver Rowland and de Jong blasted by the ART driver but both locked up massively under braking for Turn 1.
De Jong ran wide and dropped to 15th, while Rowland lost momentum and fell to third behind ART team-mate Matsushita and Sergey Sirotkin.
Another three-lap safety car followed after Philo Paz Armand went off.
This time Matsushita tried a different tactic by backing the pack up at the restart, but it caused further drama when some drivers correctly accelerated when passing the safety car line while others remained at Matsushita's speed.
This caused Gustav Malja to hit the back of Mitch Evans, sending parts of the Rapax car's front wing into the air.
Malja then clattered into Rowland, who spun but stayed in the race, while Evans and his Campos team-mate Sean Gelael also retired after hitting the barriers alongside Malja.
When the race restarted for a third time, Raffaele Marciello, who had risen to second in the confusion of the previous restart, steamed up the inside of Matsushita but locked up and was hit by the ART driver as he turned in to the left-hander.
The collision handed the lead to 18th-place starter Gasly, with Giovinazzi sensationally running second after being down in 21st following his poor start.
The Prema pair ran clear at the front during the final five-lap sprint to the flag and Giovinazzi stalked his team-mate for the lead but did not appear to be able to use his DRS.
After lining up several moves, Giovinazzi grabbed the lead on the final lap when Gasly locked up and ran wide trying to defend into the first corner.
Sirotkin finished third despite losing chunks of his front wing by hitting Matsushita at the controversial second restart, which will be investigated after the race, with King recovering to fourth.
Artem Markelov came home fifth ahead of Sergio Canamasas. Nabil Jeffri finished seventh to score his first ever GP2 points.
Markelov now leads the championship from Norman Nato, who failed to finish for the second time in two races in Baku, with Giovinazzi up to third.
RESULTS - 21 LAPS:
|1||Antonio Giovinazzi||Prema Racing||44m49.606s|
|2||Pierre Gasly||Prema Racing||1.763s|
|3||Sergey Sirotkin||ART Grand Prix||4.179s|
|4||Jordan King||Racing Engineering||5.672s|
|5||Artem Markelov||RUSSIAN TIME||14.809s|
|7||Nabil Jeffri||Arden International||17.693s|
|11||Raffaele Marciello||RUSSIAN TIME||23.645s|
|14||Daniel de Jong||MP Motorsport||52.851s|
|15||Oliver Rowland||MP Motorsport||1 Lap|
|-||Nobuharu Matsushita||ART Grand Prix||Retirement|
|-||Mitch Evans||Pertamina Campos Racing||Retirement|
|-||Sean Gelael||Pertamina Campos Racing||Retirement|
|-||Philo Paz Armand||Trident||Retirement|
|-||Norman Nato||Racing Engineering||Retirement|
|-||Jimmy Eriksson||Arden International||Retirement|
|16||Daniel de Jong||6|
|22||Philo Paz Armand||0|