Just eighteen hours earlier, Monza had been scorchingly hot in the dazzling sunlight of early September in northern Italy, by contrast, on Sunday morning the Autodromo Nazionale di Monza looked more like it was a wet Bank Holiday weekend in Clacton. Temperatures had plummeted and the skies were dark and foreboding where they weren't simply a leaden gunmetal grey as the 26 cars of the 2013 GP2 Series lined up on the grid one more time for the morning sprint race.
Alexander Rossi had claimed pole position under reverse grid rules after finishing eighth in the previous days feature event, and remarkably there hadn't been any penalties or changes to the grid handed out overnight despite a large number of incidents reported to be under investigation by the race stewards. The American duly lined up on the front row alongside Hilmer Motorsport's Adrian Quaife-Hobbs, while Jake Rosenzweig was forced to start from pit lane after stalling at the start of the formation lap.
When the lights went out, Rossi struggled to launch the Caterham car off the grid and instead it was Quaife-Hobbs who escaped into the long run to the tricky turn 1 chicane that had done so much damage in other support races over the weekend. Behind the front row, James Calado's ART stuttered and stalled which meant some frantic avoidance action as the rest of the field were channelled to the suddenly narrow right-hand side of the track to squeeze past the becalmed Briton and give chase to Quaife-Hobbs.
Saturday runner-up Sam Bird had the best of it, and by the entrance to turn 1 the Russian Time car was around the outside of the DAMS of Stephane Richelmi and up alongside the Racing Engineering car of Julian Leal, but the first chicane gave the group no room to fully resolve their battle cleanly. Richelmi was squeezed out and his front wing tipped Bird into a slide through the first chicane. Leal came out the best to consolidate second place while Bird grouped in time to hold off the recovering Rossi; Richelmi meanwhile limped back to pit lane for a new nose where he was joined by his team mate Marcus Ericsson who had picked up a left rear puncture on the opening lap.
Behind this battle, Bird's team mate Tom Dillmann was able to hold off championship leader Fabio Leimer in the second Racing Engineering car, while Rio Haryanto had made the best of the starting grid chaos to launch himself into eighth position from 13th on the grid putting the Barwa Addax ahead of Johnny Cecotto Jr (Arden) and Sergio Canamasas (Caterham). Outside the top ten, Rapax's Stefano Coletti had picked up seven places from his grid position, but could than make no further progress from there and instead fell into a highly entertaining running battle with Felipe Nasr which was eventually settled in the Carlin man's favour - but with both drivers out of the points.
Quaife-Hobbs was pulling out a strong lead at the front with Julian Leal untroubled in second but Bird with his hands full under pressure from a now fully recovered Rossi. The running order stabilised over the first eight laps with most cars too evenly matched to make successful passes, with Dani Clos the exception to the rule as he managed to pass Canamasas for ninth through Curva Grande albeit at the cost of damage to his front wing.
But then a new factor came into play as rain started to fall on the start/finish straight at the start of lap 9. Reassured that the showers would be brief, none of the leaders were tempted to pit, but it made for increasingly tricky conditions - one slip and multiple positions could be lost. No where was that more clearly demonstrated at the front, as Leal and Bird ran out of traction into the first chicane on turn 10 and had to overshoot, which allowed Alexander Rossi to sail round on the normal racing line and slip ahead of them both in one move and take up second place.
The forecasts proved correct and the rain soon ceased, with the track drying in no time as evidenced by how quickly the lap times were soon picking up again. Quaife-Hobbs and Rossi were soon trading fastest laps, but it was soon clear that the Briton has the measure of his opponent and he was never under serious threat of losing the lead - except at the very last corner when he allowed himself to drift out too wide and flirted dangerously with the grass and gravel, but fortunately he gather it up again and crossed the line in first place to claim his first win in the GP2 Series.
Behind Rossi, Julian Leal spent the second half of the race with Sam Bird firmly clamped to his rear wing, but the Briton never had a convincing opportunity to pull off a pass and eventually had to settle for just missing the podium. His team mate Dillmann came across the line behind them, with Fabio Leimer another three seconds further back and putting the clear air in which had found himself in the closing laps to good use by setting the fastest lap of the race for some valuable extra bonus points to see him take a six point lead over Bird to the penultimate round of the 2013 season in Singapore in two weeks time.