Richard Cooper was fastest out of the blocks as the Donington Park action began, leading Edoardo Colombi in FP1 with a best lap of 1min 43.053secs.
Colombi, who was the man to beat at the opening round a fortnight ago, ended the session 1.914secs adrift, with Aaron Silvester third.
Fourth quickest was Rhys Stephenson, with Lewis Arrowsmith fifth.
Pirelli National Sportbike with Moneybarn Vehicle Finance, FP1:
1. Richard Cooper (PHR Performance Triumph) 1min 43.053s
2. Edoardo Colombi (Gradara Corse Asd) +1.914s
3. Aaron Silvester (MH Solutions/Macadam Racing Triumph) +2.584s
4. Rhys Stephenson (Rocket Racing) +3.316s
5. Lewis Arrowsmith (Arrowsmith Racing) +4.042s