Formula 2 championship leader Mirko Bortolotti recorded the fastest time in first free practice at the Red Bull Ring in Austria.
The Austro-Italian driver set a quickest time of 1:23.312s during the middle of the session. Christopher Zanella, his nearest rival for the title, went second fastest towards the end, two tenths shy.
Jack Clarke, fresh from his maiden victory last time out at Brands Hatch, was third quickest, with Mihai Marinescu and Ramon Pineiro rounding out the top five.
Benjamin Lariche was a strong sixth, just ahead of Tobias Hegewald. GP3 convert Luciano Bacheta was eighth in his first session, with Alex Brundle and Julian Theobald rounding out the top ten.
South Korea's Sunghak Mun was 11th, while Miki Monras languished down in 15th. Local driver Rene Binder, making a one-off appearance, was 18th.
Free Practice 1 results:
1. Mirko Bortolotti, 1:23.312s
2. Christopher Zanella, +0.221s
3. Jack Clarke, +0.289s
4. Mihai Marinescu, +0.313s
5. Ramon Pineiro, +0.575s
6. Benjamin Lariche, +0.669s
7. Tobias Hegewald, +0.679s
8. Luciano Bacheta, +0.729s
9. Alex Brundle, +0.848s
10. Julian Theobald, +1.038s