MotoGP leader Dovizioso heads Vinales in tight Sachsenring FP1

Rossi's Yamaha stopped at Turn 6 just 15 minutes into the session, the result of a suspected electronic issue.

The Italian was able to rejoin the session on his second bike soon after but could only manage the 16th-fastest time.

Despite the presence of torrential rain on Thursday, Friday's first practice session took place in dry conditions.

Marc Marquez, who is unbeaten at Sachsenring since he stepped up to MotoGP in 2013, quickly established himself at the top of the order early on, first with a time of 1m23.344s before improving to a 1m22.265s.

But his advantage was gradually eaten into by the rest of the field before he was first usurped by Vinales and then Dovizioso at the head of the order.

Marquez and then Vinales both fought back to lead the way during the final 10 minutes, but Dovizioso eventually ended the session with the fastest time with a best lap of 1m21.599s - leaving him 0.038 seconds clear of Vinales.

Despite his early pace, Marquez was demoted to sixth by the flag as his Honda factory team-mate Dani Pedrosa, Aprilia's Aleix Espargaro and Aspar Ducati's Alvaro Bautista all edged ahead.

Bautista, as well as Scott Redding, crashed at Turn 11 at the very end of the session.

Other riders to fall were Andrea Iannone, also at Turn 11, and Tito Rabat, who ran off track at Turn 8 and lost control on the grass runoff - still damp after Thursday's rain.

Tech 3 Yamaha's Johann Zarco and Pramac Ducati's Danilo Petrucci, whose session started with an excursion through the gravel trap at the first corner, were seventh and eighth respectively.

Jack Miller and Redding completed the top 10, which was separated by less than half a second.

Jonas Folger kicked off his first home MotoGP round in 11th, narrowly edging out the second factory Ducati of Jorge Lorenzo.

FIRST PRACTICE RESULTS: