Track conditions were dry following the first Formula 1 session, and conditions were ideal for quick times from the off.
Jolyon Palmer was first to set the fastest time for Carlin, soon toppled by reigning Formula Renault 3.5 champion Robin Frijns (Hilmer).
But Nasr soon stamped his authority on the session with his 1m30.103s lap that would stand as the quickest in the session.
James Calado went second fastest on 1m30.864s in his re-liveried ART Grand Prix entry, 0.761s off Nasr's pace, with Johnny Cecotto Jr third fastest for Arden International.
Palmer and Frijns ended the session fourth and fifth respectively, with series leader Stefano Coletti sixth fastest, after sitting in the pits when track conditions appeared at their best.
Coletti was four places clear of title rival Fabio Leimer, whom he leads by 10 points in the championship. Leimer suffered a couple of brief off-track moments during the session.
Sam Bird was seventh fastest ahead of Russian Time team-mate Tom Dillmann, although Bird is under investigation for a possible yellow-flag infringement.
Everyone used one set of hard tyres in the session, with Dillmann's in particular showing signs of heavy wear as the track heated up.
Series returnee Jon Lancaster was a creditable 16th fastest for Hilmer, where he replaces Pal Varhaug.
Casualties in the session included Daniel de Jong, whose MP Motorsport car was pushed away at Turn 8 after stopping on his out-lap, suggesting a repeat of the electrical issues he's been suffering this year.
Simon Trummer spun off exiting Turn 12, demolishing a marker board on his first proper flying lap. He went no further.
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- Motor Racing
- Robin Frijns
- Jolyon Palmer
- Johnny Cecotto Jr