Tom Booth-Amos beat Luke Stapleford by a mere 0.067secs after a dramatic run to the finish line following a close race.
The pair had looked evenly matched throughout the 20-lap Sprint race as they swapped positions several times and it all came down to a last lap scrap.
Booth-Amos had the lead on his Gearlink Kawasaki but Stapleford made a dive down the inside at the hairpin, resulting in a last-gasp drag race to the line, which Booth-Amos was able to win.
Rhys Irwin finished third on the Astro-JJR Suzuki as Ben Currie was fourth and Jamie Perrin fifth.
In GP2, points leader Joe Collier crashed out on the Kramer leaving Cameron Fraser to take top points. Harry Rowlings was second and Lucca Allen third.
Quattro Group British Supersport & British GP2 Championships, Sprint race:
1. Tom Booth-Amos (Gearlink Kawasaki)
2. Luke Stapleford (Profile Road & Racing Performance) +0.067s
3. Rhys Irwin (Astro-JJR Suzuki) +1.010s
4. Ben Currie (Oxford Products Racing Ducati) +4.717s
5. Jamie Perrin (Astro-JJR Suzuki) +7.212s