Australian rider Jack Miller produced the best time in Fridays opening practice at the European MotoGP in Valencia, while championship leader Joan Mir was 17th in a wet, crash-filled session. Second-placed French rider Fabio Quartararo came 21st and last as Yamaha-SRT team-mate Franco Morbidelli, the Teruel Grand Prix winner two weeks ago, was second quickest behind Ducatis Miller. Factory Honda pair Stefan Bradl and Alex Marquez were third and fifth respectively, with Frenchman Johann Zarco fourth on his Ducati-Avintia. Quartararo, who faded badly after starting two of the past three races on pole, showed his frustration by banging his fist on his fuel tank after sliding off the track in soggy conditions. The forecast is expected to improve for the second session later on Friday (1330 GMT) but riders could be affected by the wind. Mir, who leads the championship by 14 points, fared little better than Quartararo and finished 1.6 seconds adrift of Miller in 17th place. Garrett Gerloff, deputizing for Valentino Rossi, was one spot higher in 16th. Seven-time MotoGP champion Rossi is awaiting the results of a Covid-19 test to see if he is allowed to take part in this weekends race. Fastest times for Fridays opening practice session at the European MotoGP in Valencia: 1. Jack Miller (AUS/Ducati-Pramac) 1:42.063, 2. Franco Morbidelli (ITA/Yamaha-SRT) at 0.467sec, 3. Stefan Bradl (GER/Honda) 0.503, 4. Johann Zarco (FRA/Ducati-Avintia) 0.576, 5. Alex Marquez (ESP/Honda) 0.591, 6. Danilo Petrucci (ITA/Ducati) 0.637, 7. Pol Espargaro (ESP/KTM) 0.778, 8. Miguel Oliveira (POR/KTM-Tech3) 0.814, 9. Andrea Dovizioso (ITA/Ducati) 0.896, 10. Maverick Vinales (ESP/Yamaha) 0.946 Selected: 17. Joan Mir (ESP/Suzuki) 1.665, 21. Fabio Quartararo (FRA/Yamaha-SRT) 2.728