Marc Marquez was quickest in the second MotoGP practice session at Jerez, ahead of morning pacesetter Aleix Espargaro.
In the hotter conditions of the afternoon, Honda rider Marquez's benchmark of 1m39.757s - which he set on only his third lap - was four tenths of Espargaro's practice one pace.
Marquez's only issue came after the chequered flag, when he stalled his bike while attempting a practice start and required help from the marshals.
Jerez is the only current MotoGP track where the reigning champion has not yet won a race at some stage during his career.
Espargaro jumped up to second on his Forward Yamaha late on, lapping 0.216 seconds adrift of Marquez.
That moved the Ducati of Andrea Dovizioso - another late improver - down to third, with long-time second-place man Valentino Rossi in fourth ahead of Yamaha team-mate Jorge Lorenzo.
Last year's Jerez winner Dani Pedrosa was sixth.
Alvaro Bautista, Stefan Bradl, Andrea Iannone and Nicky Hayden completed the top 10.
Hiroshi Aoyama, Bradley Smith and Hector Barbera all had late crashes. Smith's was the most destructive, but fortunately he was clear of his Tech 3 Yamaha before it began tumbling violently through the gravel.
Cal Crutchlow was 15th as he continued to assess the condition of the hand injury that prevented him from racing in Argentina last weekend.
Folllow all the action from MotoGP race day at Jerez with AUTOSPORT Race Centre Live on Sunday. Coverage starts from Moto3 and Moto2 from 10am UK time
Pos Rider Bike Time Gap Laps
1. Marc Marquez Honda 1m39.757s 18
2. Aleix Espargaro Forward Yamaha 1m39.973s +0.216s 17
3. Andrea Dovizioso Ducati 1m40.028s +0.271s 19
4. Valentino Rossi Yamaha 1m40.125s +0.368s 20
5. Jorge Lorenzo Yamaha 1m40.133s +0.376s 18
6. Dani Pedrosa Honda 1m40.491s +0.734s 19
7. Alvaro Bautista Gresini Honda 1m40.616s +0.859s 19
8. Stefan Bradl LCR Honda 1m40.672s +0.915s 19
9. Andrea Iannone Pramac Ducati 1m40.742s +0.985s 18
10. Nicky Hayden Aspar Honda 1m40.788s +1.031s 19
11. Pol Espargaro Tech 3 Yamaha 1m40.918s +1.161s 20
12. Michele Pirro Ducati 1m40.930s +1.173s 16
13. Yonny Hernandez Pramac Ducati 1m41.092s +1.335s 17
14. Hiroshi Aoyama Aspar Honda 1m41.188s +1.431s 15
15. Cal Crutchlow Ducati 1m41.353s +1.596s 16
16. Bradley Smith Tech 3 Yamaha 1m41.360s +1.603s 17
17. Scott Redding Gresini Honda 1m41.465s +1.708s 17
18. Danilo Petrucci Ioda Aprilia 1m41.589s +1.832s 15
19. Hector Barbera Avintia FTR-Kawasaki 1m41.619s +1.862s 14
20. Colin Edwards Forward Yamaha 1m41.831s +2.074s 15
21. Michael Laverty PBM Aprilia 1m41.914s +2.157s 17
22. Karel Abraham Cardion Honda 1m41.934s +2.177s 17
23. Mike di Meglio Avintia FTR-Kawasaki 1m42.220s +2.463s 18
24. Broc Parkes PBM Aprilia 1m42.424s +2.667s 15