Hillspeed's Kanato Le set the quickest time of the week so far in the first free practice session on Friday.
The Japanese driver usurped teammate Freddie Slater with his late effort in the first 30-minute session of the day, setting a 2m13.150s to put him 0.019s clear of the Thursday pacesetter, with times almost nine tenths of a second quicker than yesterday.
Slater had to settle for second this time around, but was three tenths clear of Elite's Will Macintyre, with Hitech TGR's Deagen Fairclough fourth and 0.025s further back.
JHR's Kai Daryanani started his day in fifth, 0.027s behind Fairclough and 0.190s clear of Hillspeed's Hiyu Yamakoshi.
Xcel's Patrick Heuzenroeder and Argenti's Yuanpu Cui were next up with Xcel's Dion Gowda and Hitech's Nikita Johnson completing a top-10 covered by 0.835s.
The second session is due to commence at 11.50 local time (10.50 UK).
GB3 Championship, partnered by the BRDC, Spa-Francorchamps Free Practice one result:
1. Kanato Le, Hillspeed, 2m13.150s
2. Freddie Slater, Hillspeed, +0.019s
3. Will Macintyre, Elite Motorsport, +0.355s
4. Deagen Fairclough, Hitech TGR, +0.380s
5. Kai Daryanani, JHR Developments, +0.407s
6. Hiyu Yamakoshi, Hillspeed, +0.597s
7. Patrick Heuzenroeder, Xcel Motorsport, +0.714s
8. Yuanpu Cui, Argenti with Prema, +0.783s
9. Dion Gowda, Xcel Motorsport, +0.830s
10. Nikita Johnson, Hitech TGR, +0.835s
Click here for full result.