Artem Markelov won a chaotic Monaco Formula 2 feature race, benefitting from leaders Alexander Albon and Nyck de Vries colliding on the entry to the pitlane.
From first and second on the grid, Albon and de Vries ran in the top two positions in the first 11 laps of the race when the safety car came out.
The interruption was caused by Lando Norris hitting Ralph Boschung, who had just rejoined from his tyre change, at the final corner.
Albon and de Vries quickly reacted to the safety car by entering the pits, but with the two cars running very close to each other, de Vries dived into the pitlane slightly earlier and made contact with Albon, sending the Anglo-Thai driver into a spin.
Albon's DAMS car remained stationary until team mechanics turned the car around, but was out of contention by the time he rejoined the track and eventually retired in the pits.
Despite completing the pitstop and running seventh on the restart, de Vries and pulled into the pits after circulating well off the pace for several laps.
Markelov, who had been running third, inherited the lead and had a good restart ahead of Arjun Maini, Jack Aitken and Nirei Fukuzumi, all of whom were yet to do their pitstops.
Markelov's main task was to pull away from Sean Gelael, the best-placed driver who already completed his stop, so the Russian could rejoin ahead after changing tyres.
As the Russian Time driver rapidly pulled away from Maini, he managed to extend a 27.4 gap over Gelael when he made his pitstop on Lap 34 of 42 and kept the lead.
Running on a fresh set of supersofts, Markelov increased his initial 1.9s advantage to 10.7s to take his second win of the season and also in Monaco.
Gelael secured his second F2 podium finish as the best driver on the early-pitting strategy.
Norris was right behind Gelael when he received a drive-through for hitting Boschung. That promoted Roberto Merhi into the last spot on the podium with Louis Deletraz taking fourth.
However Norris still secured sixth, narrowly losing out to Maini when the Indian completed his late stop.
Aitken took seventh with Antonio Fuoco finishing eighth to start Saturday's sprint race from pole.
Fuoco recovered from forcing Luca Ghiotto into the wall at the start, which caused the first of two safety car stints in the race, and receiving a drive-through penalty.
Nicholas Latifi was the last driver to change tyres and ended up ninth from 18th and last on the grid.
Arden's Nirei Fukuzumi took the final point-scoring position just ahead of teammate Maximilian Gunther, who started the race from the pitlane after he was excluded from qualifying due to not stopping at the weighbridge.
Mercedes F1 junior George Russell gained four places in the early laps to run 12th, but diving to the inside of Fukuzumi at Rascasse resulted in the ART driver hitting the wall and retiring.
Santino Ferrucci stalled on the grid and was later given a five-second time penalty for speeding in the pitlane on his way to 13th.
|1||Artem Markelov||RUSSIAN TIME||-|
|2||Sean Gelael||Prema Powerteam||10.7|
|3||Roberto Merhi||MP Motorsport||15.4|
|4||Louis Deletraz||Charouz Racing System||19.2|
|7||Jack Aitken||ART Grand Prix||21.9|
|8||Antonio Fuoco||Charouz Racing System||23.8|
|10||Nirei Fukuzumi||Arden International||30.9|
|11||Maximilian Gunther||Arden International||31.5|
|12||Roy Nissany||Campos Racing||49.7|
|Ret||Tadasuke Makino||RUSSIAN TIME||3 laps|
|Ret||Alexander Albon||DAMS||20 laps|
|Ret||Nyck de Vries||Prema Powerteam||23 laps|
|Ret||Ralph Boschung||MP Motorsport||31 laps|
|Ret||George Russell||ART Grand Prix||37 laps|
|Ret||Luca Ghiotto||Campos Racing||42 laps|