Jorge Lorenzo quickest in first Mugello MotoGP practice

The current points leader led the majority of the morning, eventually reaching a time of 1m48.131s with his final lap.

Lorenzo's closest challenger ultimately proved to be Casey Stoner. The Honda rider had a quiet start, spending much of the session near the foot of the top 10, before steadily improving his pace to end up half a second down on the Yamaha.

Sachsenring winner Dani Pedrosa lost second to team-mate Stoner late on, but remained third.

Ducati's home grand prix weekend started relatively well, with Nicky Hayden fourth and Valentino Rossi sixth.

The pair were split by Tech 3 Yamaha pair Cal Crutchlow and Andrea Dovizioso, as Crutchlow made it into the top five despite stopping on track with a mechanical problem on his main bike.

Lorenzo's team-mate Ben Spies had a minor fall when he ran wide through the gravel. There was a similar incident for Gresini Honda rider Alvaro Bautista, who tried his utmost to keep his bike running through the San Donato gravel before ultimately having to tip it onto its side.

That left Bautista at the back of the prototype pack - which is only 11 bikes this weekend with the injured Karel Abraham's Cardion Ducati absent.

Aspar's Randy de Puniet and Aleix Espargaro led the CRT field.

Pos Rider             Team/Bike                 Time       Gap
 1. Jorge Lorenzo     Yamaha                    1m48.131s
 2. Casey Stoner      Honda                     1m48.649s  + 0.518s
 3. Dani Pedrosa      Honda                     1m48.877s  + 0.746s
 4. Nicky Hayden      Ducati                    1m48.981s  + 0.850s
 5. Cal Crutchlow     Tech 3 Yamaha             1m49.023s  + 0.892s
 6. Andrea Dovizioso  Tech 3 Yamaha             1m49.038s  + 0.907s
 7. Valentino Rossi   Ducati                    1m49.074s  + 0.943s
 8. Hector Barbera    Pramac Ducati             1m49.166s  + 1.035s
 9. Ben Spies         Yamaha                    1m49.398s  + 1.267s
10. Stefan Bradl      LCR Honda                 1m49.438s  + 1.307s
11. Alvaro Bautista   Gresini Honda             1m49.688s  + 1.557s
12. Randy De Puniet   Aspar Aprilia             1m50.949s  + 2.818s
13. Aleix Espargaro   Aspar Aprilia             1m51.101s  + 2.970s
14. Mattia Pasini     Speed Master Aprila       1m51.253s  + 3.122s
15. Michele Pirro     Gresini FTR-Honda         1m51.835s  + 3.704s
16. Yonny Hernandez   Avintia BQR-Kawasaki      1m51.973s  + 3.842s
17. Colin Edwards     Forward Suter-BMW         1m52.154s  + 4.023s
18. Danilo Petrucci   Ioda-Aprilia              1m52.952s  + 4.821s
19. James Ellison     Paul Bird Aprilia         1m53.390s  + 5.259s
20. Ivan Silva        Avintia Inmotec-Kawasaki  1m53.931s  + 5.800s