Stefan Bradl set a surprise fastest time in the second MotoGP practice session at Brno.
Morning pacesetter Jorge Lorenzo had looked set to stay on top, only for Bradl to pop in a 1m56.500s as the checkered flag came out. That deposed the world champion's Yamaha by just 0.038 second.
Bradl's time came on a late run back on soft tires after he had earlier tried hards and been dissatisfied. Lorenzo led an all-Yamaha top three in the opening stages, but the Hondas gradually crept forward. Dani Pedrosa ended up third, 0.062s behind Lorenzo.
Championship leader Marc Marquez jumped to second for a spell, before finishing the day in fifth as Valentino Rossi's last lap got him ahead.
Cal Crutchlow completed the top six, having been Lorenzo's closest rival in the early stages, with his Tech 3 Yamaha teammate Bradley Smith next up.
Aleix Espargaro led the CRT field by over a second, and got ahead of Ben Spies' Pramac stand-in Michele Pirro's prototype Ducati.
Pos Rider Team/Bike Time Gap
1. Stefan Bradl LCR Honda 1m56.500s
2. Jorge Lorenzo Yamaha 1m56.538s +0.038s
3. Dani Pedrosa Honda 1m56.600s +0.100s
4. Valentino Rossi Yamaha 1m56.726s +0.226s
5. Marc Marquez Honda 1m56.733s +0.233s
6. Cal Crutchlow Tech 3 Yamaha 1m56.800s +0.300s
7. Bradley Smith Tech 3 Yamaha 1m57.351s +0.851s
8. Alvaro Bautista Gresini Honda 1m57.401s +0.901s
9. Andrea Dovizioso Ducati 1m57.754s +1.254s
10. Nicky Hayden Ducati 1m57.896s +1.396s
11. Andrea Iannone Pramac Ducati 1m58.039s +1.539s
12. Aleix Espargaro Aspar Aprilia 1m58.217s +1.717s
13. Michele Pirro Pramac Ducati 1m58.958s +2.458s
14. Hector Barbera Avintia FTR-Kawasaki 1m59.235s +2.735s
15. Claudio Corti Forward FTR-Kawasaki 1m59.288s +2.788s
16. Colin Edwards Forward FTR-Kawasaki 1m59.390s +2.890s
17. Yonny Hernandez PBM Aprilia 1m59.539s +3.039s
18. Hiroshi Aoyama Avintia FTR-Kawasaki 1m59.613s +3.113s
19. Danilo Petrucci Ioda-Suter-BMW 1m59.719s +3.219s
20. Randy de Puniet Aspar Aprilia 1m59.799s +3.299s
21. Michael Laverty PBM-Aprilia 2m00.338s +3.838s
22. Karel Abraham Cardion Aprilia 2m00.413s +3.913s
23. Martin Bauer Remus Aprilia 2m00.730s +4.230s
24. Lukas Pesek Ioda-Suter-BMW 2m01.549s +5.049s
25. Bryan Staring Gresini FTR-Honda 2m01.746s +5.246s