Marc Marquez was fastest despite a late fall as MotoGP's Mugello weekend began with a damp free practice session.
Heavy overnight rain meant it was only in the final few minutes that slicks could be used, and not all the front-runners felt it was worth trying them.
Marquez put his Honda on top by over a second for a while as he led progress towards competitive dry times, although his final 1m54.797s was still seven seconds down on last year's pole. He ran off the track after setting that time, keeping his Honda upright through the gravel only to then fall when he tried to cross the wet grass back onto the track. The Spaniard was unhurt and managed to bump-start his bike and rejoin.
The order was predictably unusual as timing of slick laps decided the standings.
Ducati test rider Michele Pirro took second, followed by LCR Honda's Stefan Bradl and CRT duo Karel Abraham (Cardion) and Yonny Hernandez (Paul Bird). The latter was fastest overall for a spell.
Championship leader Dani Pedrosa set the best wet-tyre time of the morning, but ended up eighth.
The Yamahas did not try slicks, leaving Jorge Lorenzo and Valentino Rossi 14th and 19th.
Andrea Dovizioso crashed his Ducati at the first turn without drama. Ioda teammate Lukas Pesek and Danilo Petrucci were the others to fall.
Pos Rider Team/Bike Time Gap
1. Marc Marquez Honda 1m54.797s
2. Michele Pirro Ducati 1m55.195s + 0.398s
3. Stefan Bradl LCR Honda 1m55.288s + 0.491s
4. Karel Abraham Cardion Aprilia 1m55.874s + 1.077s
5. Yonny Hernandez PBM Aprilia 1m55.907s + 1.110s
6. Bradley Smith Tech 3 Yamaha 1m55.981s + 1.184s
7. Nicky Hayden Ducati 1m55.991s + 1.194s
8. Dani Pedrosa Honda 1m56.534s + 1.737s
9. Cal Crutchlow Tech 3 Yamaha 1m56.984s + 2.187s
10. Ben Spies Pramac Ducati 1m57.045s + 2.248s
11. Alvaro Bautista Gresini Honda 1m57.910s + 3.113s
12. Aleix Espargaro Aspar Aprilia 1m58.076s + 3.279s
13. Andrea Iannone Pramac Ducati 1m58.478s + 3.681s
14. Jorge Lorenzo Yamaha 2m00.174s + 5.377s
15. Andrea Dovizioso Ducati 2m00.457s + 5.660s
16. Hiroshi Aoyama Avintia FTR-Kawasaki 2m00.801s + 6.004s
17. Colin Edwards Forward FTR-Kawasaki 2m01.082s + 6.285s
18. Randy de Puniet Aspar Aprilia 2m01.108s + 6.311s
19. Valentino Rossi Yamaha 2m01.455s + 6.658s
20. Hector Barbera Avintia FTR-Kawasaki 2m02.673s + 7.876s
21. Lukas Pesek Ioda-Suter-BMW 2m04.160s + 9.363s
22. Bryan Staring Gresini FTR-Honda 2m04.511s + 9.714s
23. Danilo Petrucci Ioda-Suter-BMW 2m05.741s + 10.944s
24. Michael Laverty PBM-Aprilia 2m05.759s + 10.962s
25. Claudio Corti Forward FTR-Kawasaki 2m06.323s + 11.526s