Marco Bezzecchi led the way for Ducati in first practice for the Dutch TT at Assen.
The VR46 rider posted the fastest lap in 1:32.246s on the opening day at the eighth round of the MotoGP World Championship to lead Aprilia Racing’s Maverick Vinales by 0.314s.
Repsol Honda’s Marquez, who sat out the main race at the Sachsenring in Germany last Sunday after fracturing a thumb in morning warm-up – his fifth of a disastrous weekend – was languishing in 19th and eventually dropped to a lowly 21st as he made a tentative start to the weekend.
Gresini Ducati’s Alex Marquez slotted into third, around five hundredths of a second behind Vinales, with Johann Zarco fourth quickest on the Pramac Ducati.
Zarco rebounded from a crash to break to force his way into the top four, with the French rider hitching a lift back to the paddock on the rear of Jack Miller’s KTM.
Fabio Quartararo will be encouraged by his early pace on the Monster Energy Yamaha, ending the session in fifth, while Luca Marini rounded out the first six on the VR46 Ducati.
Enea Bastianini had made the early running in the 45-minute session on the Lenovo Ducati from Marini, but he ended opening practice down in 17th after crashing at Turn 10 with 18 minutes to go. Bastianini was unhurt but his factory Ducati was heavily damaged in the incident.
Championship leader Francesco Bagnaia, who won at Assen last year, showed his frustration by slapping the tank of his GP23 after making some unforced errors on the Lenovo Ducati.
The Italian had to sit up at Turn 6 after getting it wrong and again made a mistake at the same part of the course later in the session. He climbed to sixth before making an error at Turn 1.
His woes continued when he was on a fast lap with around four minutes to go, with a fuming Bagnaia banging the tank again after his machine got out of shape at the fast Turn 15.
Bagnaia will be eager to make improvements in the afternoon session after only managing the 12th fastest time.
Outside the top six, Takaaki Nakagami was seventh on the LCR Honda ahead of Sachsenring double winner Jorge Martin (Pramac Ducati), while Aussie Miller was the leading KTM rider on the Red Bull machine in ninth.
Aleix Espargaro (Aprilia Racing) claimed 10th in the morning session ahead of Miller’s KTM team-mate Brad Binder.
Stefan Bradl and World Superbike rider Iker Lecuona, replacing injured Honda riders Alex Rins and Joan Mir at Assen in the LCR and Repsol teams, were 19th and 22nd respectively.