Marquez is now on course to end the 2014 MotoGP season in the same dominant fashion that has seen him clinch the title with ease.
The Spaniard defended his crown in style with the Repsol Honda rider having won 12 of the previous 17 rounds of the year.
His time of one minute 31.296 seconds in the morning session was the fastest of the day with compatriot Jorge Lorenzo’s Movistar Yamaha second quickest on a good day for the local fans.
Andrea Dovizioso was third fastest following his effort in free practice two on his Ducati, with Aleix Espargaro (NGM Forward Racing) and Marquez’s team-mate Dani Pedrosa rounding out the top five.
Cal Crutchlow was sixth on the second Ducati with Valentino Rossi, Stefan Bradl, Pol Espargaro and Bradley Smith all managed times good enough for the top 10.