Trident's David Beckmann dominated a sodden Italian feature race where he led the race from start to finish with little challenge from the rest of the pack over the 22 laps.
The German driver immediately sought to defend his position by chopping across the face of championship leader Anthoine Hubert in second place and then proceeded to storm away from the rest of the pack.
As Beckmann got away well there was a flurry of action behind as numerous cars took to the escape road having out-braked themselves on the standing water in the braking zones, with Tatiana Calderon going into the back of Jenzer team-mate Juan Manuel Correa twice in consecutive corners.
Hubert ended the race in second after he was unable to keep up with the Trident ahead of him but once again widened his championship lead over ART team-mate Callum Ilott in third.
The British driver rounded off the podium after getting passed by Nikita Mazepin at the halfway point of the race after the Russian ran wide at the Della Roggia chicane.
Simo Laaksonen flourished in the changing conditions as the track began to dry, the Finnish driver stormed through the field having started the race down in 14th position, Mazepin had to settle for fifth place behind the Campos as he looked to be struggling with tyre wear as the track dried out.
Ferrari-backed Giuliano Alesi got a poor getaway at the start of the race falling back into the pack but was able to show good form and patience in the tricky conditions to claw his way back to sixth place.
Trident's Pedro Piquet crossed the line in seventh ahead of MP Motorsport's Richard Verschoor in eighth who continues to acquit himself well in the series after only making his debut at the last round in Belgium. The Dutch driver will start the Sunday's sprint race on pole position.
ART's Jake Hughes again improved on his qualifying position to take the chequered flag in ninth place ahead of Niko Kari rounding out the top 10.
Sunday's sprint race will get underway at 9:40am local time.
