Billy McConnell topped the timesheets in FP1 as he stormed to a 1min 31.840sec lap in the final seconds to knock points rival Alex Olsen down to second.
Charlie Nesbitt emerged best of the rest as he ended the first session in third position, just ahead of title leader Davey Todd as Richard Kerr just beat Dan Linfoot to fifth.
Pirelli National Superstock Championship with MotoNovo, Donington Park, FP1:
1. Billy McConnell (C&L Fairburn Properties/Jackson Racing) 1min 31.840s
2. Alex Olsen (FHO Racing with Kobelco) +0.168s
3. Charlie Nesbitt (VisionTrack Suzuki) +0.281s
4. Davey Todd (Milenco by Padgetts Motorcycles) +0.513s
5. Richard Kerr (AMD Motorsport) +0.758s