Having grabbed the lead at the first corner, Carlin racer Nasr won the Sprint race by five seconds from Johnny Cecotto Jr, who passed Palmer's DAMS car for second on lap two and took the fight to Nasr thereafter.
Trident's Cecotto got to within 0.6s of Nasr, but was never quite close enough to attempt a pass, and dropped well back in the closing stages as Nasr secured the bonus point for fastest lap.
Behind Palmer, Mitch Evans took fourth place right at the end for Russian Time when Hilmer's poleman Daniel Abt suffered a technical issue at Raidillon that handed him the position.
Vandoorne: I had to dominate GP2
12/10/2015 AT 14:55
Stoffel Vandoorne finished sixth for ART, ahead of a charging Stefano Coletti, who came through to finish seventh from 24th on the grid.
His Racing Engineering team-mate Raffaele Marciello, who won yesterday, spun on the opening lap and could only recover to 14th.
Palmer still leads the standings, but by the reduced margin of 32 points over Nasr.
Vandoorne seals GP2 title in Russia
11/10/2015 AT 09:17
Rossi wins after Lynn crashes out
10/10/2015 AT 15:37