Light drizzle interrupted proceedings for 12-minutes but shortly afterwards they were back on the track.
Towards the end of the session a whole lot of riders improved their times which pushed Lorenzo to the bottom of the top 10 in combined times.
However a late effort then sent him to first place but moments later Rossi was quicker to beat the Spaniards time by 0.108 seconds to grab top spot in the session.
Ducati’s Andrea Iannone and Andrea Dovizioso were third and fourth respectively ahead of Tech 3 Yamaha rider Bradley Smith.
Marc Marquez came in sixth fastest followed by Honda team-mate Dani Pedrosa.
FREE PRACTICE TIMES
1. Valentino Rossi Yamaha 1'33.167s
2. Jorge Lorenzo Yamaha 0.108s
3. Andrea Iannone Ducati 0.125s
4. Andrea Dovizioso Ducati 0.189s
5. Bradley Smith Tech 3 Yamaha 0.220s
6. Marc Marquez Honda 0.310s
7. Daniel Pedrosa Honda 0.341s
8. Maverick Vinales Suzuki 0.359s
9. Pol Espargaro Tech 3 Yamaha 0.493s
10. Cal Crutchlow LCR Honda 0.577s
11. Danilo Petrucci Pramac Racing Ducati 0.636s
12. Aleix Espargaro Suzuki Suzuki 0.787s
13. Stefan Bradl Forward Racing Yamaha Forward 1.028s
14. Scott Redding Marc VDS Honda 1.056s
15. Hector Barbera Avintia Racing Ducati 1.239s
16. Yonny Hernandez Pramac Racing Ducati 1.273s
17. Alvaro Bautista Aprilia Gresini Aprilia 1.501s
18. Mike Di Meglio Avintia Racing Ducati 1.846s
19. Eugene Laverty Aspar Honda 1.859s
20. Nicky Hayden Aspar Honda 2.010s
21. Jack Miller LCR Honda 2.253s
22. Loris Baz Forward Racing Yamaha Forward 2.863s
23. Alex de Angelis IodaRacing Project ART/Aprilia 3.131s
24. Marco Melandri Aprilia Gresini Aprilia 4.222s