Jack Kennedy coasted to his 12th win of the season as he beat Jamie van Sikkelerus by 8.737secs to put one hand on the championship trophy.
And as title rival Bradley Perie crashed out on the final lap, Kennedy is now in an even stronger position to lift the title tomorrow.
It was another solid win for the Mar-Train Racing rider, who grabbed the holeshot from pole and was never challenged as he powered to yet another win, beating Dutchman van Sikkelerus as Lee Johnston took third on his return to action.
Harry Truelove crossed the line fourth on the Appleyard Macadam Yamaha as Jack Scott was fifth, and first GP2 rider home.
Cameron Fraser emerged best of the rest of the GP2 runners as he finished second in class and 14th overall, one place ahead of the third GP2 bike of Harvey Claridge.
Quattro Group British Supersport & British GP 2 Championship, Snetterton, Sprint Race:
1. Jack Kennedy (Mar-Train Racing)
2. Jamie van Sikkelerus (MPM Routz Racing) +8.737s
3. Lee Johnston (Ashcourt Racing) +9.394s
4. Harry Truelove (Appleyard Macadam Racing) +12.430s
5. Jack Scott (One-Kovara Projects/RS Racing) +13.566s