Mihai Marinescu started the FIA Formula Two Championship round at Brands Hatch on top by setting the pace in first practice, while Hector Hurst was a strong second on home soil.
Earlier rain showers left the Kent circuit damp but drying at the start of the session, as Marinescu topped the times early on ahead of championship leader Luciano Bacheta.
The session was briefly halted after Markus Pommer stopped on track, before Christopher Zanella went quickest, only to have his time bettered by fellow Swiss driver Matheo Tuscher.
The red flags made a second appearance when David Zhu spun at Paddock Hill Bend, leaving five minutes of the session remaining when it got going again.
Hampshire racer Hurst then went quickest, but not for long as Marinescu (fourth in the standings at the halfway stage of the season) returned to P1. The Romanian bettered Hurst by 0.340s, with the Briton pipping Tuscher for second by just six thousandths of a second.
Zanella finished up fourth, with Slough-born Zimbabwean driver Axcil Jefferies taking fifth, eight tenths off the pace. Kevin Mirocha was sixth.
Alex Fontana was seventh, while Mauro Calamia ran well to go eighth behind his compatriot and ensure all four Swiss drivers were in the top ten. Bacheta ended up down in ninth, just ahead of Plamen Kralev.
Remaining British drivers Dino Zamparelli and Daniel McKenzie will look to improve on 11th and 12th this weekend, while Max Snegirev and Kourosh Khani were 13th and 14th. Zhu and Pommer rounded out the 16 runners.