VRD Racing by Arden's Noah Ping set the pace in the opening test session of the week on the Silverstone Grand Prix circuit.
Ping's best time came on his ninth lap of the session, with his 1m53.340s putting him 0.063s clear of teammate and Zandvoort race winner Nikita Johnson.
The two Americans were half a second clear of the rest of the pack, which was headed by Elite Motorsport's Jarrod Waberski, who was half a tenth ahead of Rodin Motorsport's title challenger Louis Sharp.
Shawn Rashid ensured all three VRD Racing by Arden cars were represented inside the top-five, just a tenth of a second away from Sharp's effort.
Elite Motorsport duo McKenzy Cresswell and Hugo Schwarze were next up, separated by 0.028s, while the returning Ugo Ugochukwu put his Rodin car eighth, 0.045s clear of Hitech Pulse-Eight's championship leader Tymek Kucharczyk.
The Polish driver's teammate Gerrard Xie was just 0.048s behind to complete the top-10, with the Chinese driver setting an identical lap time to Rodin's Arthur Rogeon.
Chris Dittmann Racing's series newcomer Jacob Douglas started preparations for his first GB3 event with the 20th fastest time, while Alex Kattoulas sampled a GB3 car with Fortec Motorsport and was 22nd.
The second session of the day at Silverstone is due to commence at 12.15.
GB3 Championship, partnered by the BRDC, Silverstone Thursday session one result;
1. Noah Ping, VRD Racing by Arden, 1m53.340s
2. Nikita Johnson, VRD Racing by Arden, +0.063s
3. Jarrod Waberski, Elite Motorsport, +0.570s
4. Louis Sharp, Rodin Motorsport, +0.621s
5. Shawn Rashid, VRD Racing by Arden, +0.732s
6. McKenzy Cresswell, Elite Motorsport, +0.943s
7. Hugo Schwarze, Elite Motorsport, +0.987s
8. Ugo Ugochukwu, Rodin Motorsport, +1.015s
9. Tymek Kucharczyk, Hitech Pulse-Eight, +1.060s
10. Gerrard Xie, Hitech Pulse-Eight, +1.1008s
Click here for full result.