Championship leader Alex Ninovic topped the times on a soaking wet final test day at Donington Park on Friday.
On a day interrupted by almost constant rainfall, Ninovic set his best time of 1m35.002s in the day's first session this morning, and he ended up just 0.048s clear of Hitech's Deagen Fairclough who topped the times in session three.
The second Rodin driver of Gianmarco Pradel was third quickest with his time from session one, just over three tenths of a second further back.
Hitech's Keanu Al Azhari was next up having been fastest in session two, but his time from the opening test put him fourth overall, 0.025s ahead of the third Rodin of Abbi Pulling in fifth.
Argenti with Prema's Reza Seewooruthun was next up in sixth, just 0.008s ahead of Fortec's newcomer Liam McNeilly who has constantly improved his pace ahead of hid debut weekend.
Hillspeed's Lucas Fluxa was eighth fastest, less than a tenth further back, while VRD's Enzo Tarnvanichkul and JHR's Noah Lisle completed a top-10 covered by 0.826s.
GB3 action continues with the double qualifying session tomorrow morning.
GB3 Championship, partnered by the BRDC, Donington Park Friday test combined result:
1. Alex Ninovic, Rodin Motorsport, 1m35.002s
2. Deagen Fairclough, Hitech TGR, +0.048s
3. Gianmarco Pradel, Rodin Motorsport, +0.372s
4. Keanu Al Azhari, Hitech TGR, +0.504s
5. Abbi Pulling, Rodin Motorsport, +0.529s
6. Reza Seewooruthun, Argenti with Prema, +0.565s
7. Liam McNeilly, Fox Motorsport, +0.573s
8. Lucas Fluxa, Hillspeed, +0.657s
9. Enzo Tarnvanichkul, VRD Racing, +0.794s
10. Noah Lisle, JHR Developments, +0.826s
11. Jack Sherwood, Xcel Motorsport, +0.851s
12. Patrick Heuzenroeder, Xcel Motorsport, +0.871s
13. Max Taylor, RACE LAB, +0.930s
14. Kai Daryanani, JHR Developments, +1.273s
15. Flynn Jackes, Elite Motorsport, +1.362s
16. Kabir Anurag, Xcel Motorsport, +1.506s
17. Patricio Gonzalez, VRD Racing, +1.518s
18. Bart Harrison, JHR Developments, +1.568s
19. Rodrigo Gonzalez, VRD Racing, +1.781s
20. Bianca Bustamante, Elite Motorsport, +2.535s