Valentino Rossi tops opening Assen practice

The Yamaha rider was quiet for much of the 45-minute session as Honda's Dani Pedrosa led the way with a time set inside the first quarter of an hour.

Marc Marquez began the session by crashing on his outlap on cold tyres, but he was able to get back on his Honda and return to the pits.

He later displaced team-mate Pedrosa at the top of the times inside the final five minutes, but was forced to settle for second after three consecutive fastest laps from Rossi, who ended up nearly two tenths of a second clear.

Pedrosa improved his time late on but he remained third ahead of Jorge Lorenzo.

Pol Espargaro beat Tech 3 team-mate Bradley Smith to fifth place, with the Suzuki duo of Maverick Vinales and Aleix Espargaro behind that.

Andrea Dovizioso was the best of the Ducati entries in ninth ahead of Pramac rider Danilo Petrucci. Andrea Iannone was 13th behind LCR's Jack Miller and Cal Crutchlow.