Australian MotoGP rider Jack Miller was second after crashing out in a first practice session for the Valencia Grand Prix topped by Italy's Andrea Iannone.
Honda's Miller was the first rider to get past hometown hero Marc Marquez in the final stretch with two consecutive fast laps.
Marquez dominated a good part of the first free practice but ended in fifth, also behind Italian Andrea Dovizioso.
Iannone (Suzuki) set the pace for the first practice with a time of one minute, 31.045 seconds, 0.312 seconds clear of Miller.
A crash, however, ended Miller's participation in the first practice session, though he did not sustain any serious injuries.
Seeking his fourth world title, Marquez tops the MotoGP standings with 129 points, just five points ahead of Maverick Vinales (Yamaha).
Dovizioso sits third, six points off the pace heading into the season-ending race in Valencia.
