Luke Stapleford took charge on day one at Oulton Park as he ended the day on top after both free practice sessions.
The Macadam Triumph Racing rider held off reigning champ Ben Currie, clocking a 1min 37.168s lap, 0.241secs ahead of Currie’s Oxford Products Racing Ducati.
Third quickest was Honda Racing’s Jack Kennedy, with ROKiT Haslam Racing’s Eugene McManus fourth as Alastair Seeley rounded out the top five.
Jack Nixon was once again the man to beat in GP2, as he led his Kramer Racing team-mate Owen Jenner, with Luca Allen third.
Mikey Hardie topped the Cup times, ahead of Cameron Hall and Tom Tunstall.
Quattro Group British Supersport and GP2 Championships, Combined free practice:
1. Luke Stapleford (Macadam Racing Triumph) 1min 37.168s
2. Ben Currie (Oxford Products Racing Ducati) +0.241s
3. Jack Kennedy (Honda Racing UK) +0.243s
4. Eugene McManus (ROKit Haslam Racing) +0.814s
5. Alastair Seeley (Binch Pro Yamaha) +1.048s