Jack Doohan put in an assured performance to take the final win of the season as F2 waved farewell to the current specification chassis.
But his uneventful success was left in the shadow of a thrilling battle for championship honours between Pourchaire and Frederik Vesti.
After dominating on Saturday, Vesti fell painfully short of making back the 16-point deficit with which he had been faced, crossing the line in third after starting ninth.
Pourchaire, who had started 14th, finished fith with a stout three-lap defence when battling Vesti a period that can be pinpointed as the moment he secured his title.
The opening lap was a relatively calm affair in F2 terms with the only incident of note being Ayumu Iwasa making use of the runoff at the Turn 6-7 chicane and gaining fourth from Zane Maloney. One lap later, he handed the position back at the same place but immediately retook the place, meaning the incident was noted by race control but no further action was taken.
Needing to outscore Pourchaire by at least 16 points, Prema put Vesti on the alternate strategy, running the medium tyres in the opening stint and going long while those ahead fitted softs. Conversely, ART driver and points leader Pourchaire started on the red-walled softer option.
At the end of lap six of 33, Pourchaire pitted for mediums, removing the risk of a poorly timed safety car interruption ruining his charge.
Neither championship protagonist had made significant progress in the early laps with Vesti finding himself stuck behind the Hitech entry of Isack Hadjar. But once the Frenchman pitted at the end of lap eight, he could get the hammer down, with his Prema team urging him on and demanding the next 10 laps to be “like one big quali lap”.
Race leader Doohan pitted for mediums at the end of lap nine, returning to the track in P12.
As the drivers on fresher rubber, led by Doohan, began to close on those yet to stop, Vesti’s Prema team-mate, Oliver Bearman, retired from the race as his engine went into a self-preservation mode.
Although he was able to recover to the pitlane, his car came to a halt in the entry of the pitlane, causing it to be temporarily closed. But happy that the car was far enough out of the way, the recovery action was halted and the lane reopened.
At the end of lap 22, Vesti dove for the pits and fitted soft tyres, ready for his final push for glory or otherwise. Leaving the pits in ninth, one place behind Pourchaire, Vesti was tasked with making up the best part of 10 seconds in 11 laps.
Arthur Leclerc was the final driver to pit on lap 24, handing the lead back to Doohan.
On lap 25, Vesti and Pourchaire went wheel-to-wheel, with the former finding a way past into Turn 6 before dropping back on the run to Turn out as Pourchaire enjoyed the DRS advantage. Kush Maini also found himself in the middle of the battle, being twice run off the track before conceding to the warring rivals.
Minus the inconvenience of Maini, the situation repeated itself on the following lap. Losing time, Vesti was reminded he had “nothing to lose”.
Lap 27 saw Vesti remain behind Pourchaire along the first straight, waiting so that his rival would not have an immediate chance to pull back the position with DRS.
With Pourchaire in sixth, Vesti now needed to make up 13 seconds in six laps, to climb to P2 in order to take championship glory for himself.
But then came a further twist, with Pourchaire noted for leaving the track and gaining an advantage in the earlier battle with Maini.
Moments after Vesti took fourth from Maloney, his charge came to a sudden end as the virtual safety car was deployed to cover the recovery of Joshua Mason’s car, which had stopped on the straight opposite the support pit building.
Knowing he had fallen short, Vesti went all in when battling Maloney on the final lap, with contact sending the Red Bull-liveried car spinning as Vesti went on to take the final podium position.
Pourchaire crossed the line in fifth and was in tears on the team radio after being told his mission had been accomplished, despite having only one win to his name all season.
With Martins second, ART was also confirmed as the teams’ champion.