Rhys Irwin saw off the opposition as he powered his Performance 15 Suzuki to pole in the Snetterton sunshine.
His best lap of 1min 50.475secs was enough to keep him 0.106s clear of reigning champ Jack Kennedy, who will line up second with Ben Currie third.
Heading the second row will be Oli Bayliss, who stormed to a impressive fourth in his debut for the Macadam Triumph squad, with team-mate Luke Stapleford in fifth.
Joe Farragher was once again quickest in the Cup class, with Stephen Thomas second and Keo Walker third
Quattro Group British Supersport Championship, Qualifying:
1. Rhys Irwin (Performance 15) 1min 50.475s
2. Jack Kennedy (Honda Racing UK) +0.106s
3. Ben Currie (Moto Rapido Ducati) +0.125s
4. Oli Bayliss (Macadam Triumph Racing) +0.332s
5. Luke Stapleford (Macadam Triumph Racing) +0.534s