Jamie van Sikkelerus drew first blood as he led Damon Rees by almost two seconds in the first Supersport session.
The Dutchman’s lap of 1min 41.785secs was 1.652s clear of Rees, as youngster Ash Barnes finished the session third.
On a damp track, it was Tom Booth-Amos who ended the session fourth, just ahead of Rhys Irwin.
And it was all change in the GP2 class as former BSB man Barry Burrell set the pace in seventh position overall, just one spot ahead of Jake Archer. Mason Law was third on his return to the series.
Quattro Group British Supersport & British GP2 Cup, Donington Park, FP1:
1. Jamie van Sikkelerus (MPM Routz Racing)
2. Damon Rees (Ashcourt Racing) +1.652s
3. Ash Barnes (Barney Racing) +2.462s
4. Tom Booth-Amos (Gearlink Kawasaki) +2.738s
5. Rhys Irwin (Astro LLR-Triumph) +2.957s