Max Cook took his fifth win of the year to extend his championship points lead as he beat Sam Laffins by 3.340secs.
Cook led from the start as title rival Louis Valleley crashed out on lap two, one of many riders who were caught out on the damp track.
Third was Dan Brooks with Zak Fuller fourth and Cameron Hall fifth
Pirelli National Junior Superstock Championship with MotoNovo, Cadwell Park, Race Result:
1. Max Cook (Uggly &Co by Binch Pro)
2. Sam Laffins (Cheshire Mouldings Kawasaki by JR Performance) +3.340s
3. Dan Brooks (R4R Vision Team) +6.095s
4. Zak Fuller (G&S Racing) +9.583s
5. Cameron Hall (Triple M Vehicle Sales) +9.702s
Championship positions after Round Nine:
1. Max Cook 165
2. Louis Valleley 122
3. Franco Bourne 109
4. Dan Brooks 107
5. Aaron Silvester 100