Suzuki rider Andrea Iannone topped the opening practice session for MotoGP's Italian Grand Prix at Mugello, beating Ducati wildcard Michele Pirro by over half a second.

Iannone, who confirmed on Thursday he will leave Suzuki at the end of the 2018 season, left it until the final 30 seconds of the 45-minute Friday morning session to move to the top of the times, posting a best lap of 1m47.253s.

That was 0.550s up on Pirro, making his first of three planned starts on a third factory Ducati this year, who led the timesheets for the bulk of the running and ended up second.

Andrea Dovizioso made it a Ducati 1-2 for most of the way with a lap 0.192s slower than Pirro, which proved good enough for third in the final reckoning, 0.708s down on former team-mate Iannone.

Yamaha's Maverick Vinales crashed at the first corner, San Donato, on his first flying lap, but he was able to recover to set the fourth-quickest time, fractionally slower than Dovizioso.

Setting identical times were Pramac Ducati's Jack Miller and championship leader Marc Marquez on the best of the Hondas, both recording a 1m48.035s to take fifth and sixth places.

Rookie Franco Morbidelli was an impressive seventh, less than two tenths shy of Marquez and 0.007s ahead of his mentor Valentino Rossi.

Jorge Lorenzo was a further thousandth of a second behind in ninth, while Cal Crutchlow completed a top 10 split by a little under a second.

Danilo Petrucci, who is vying to replace Lorenzo at the factory Ducati team next year, had a subdued start to his home race weekend in 13th place, making him the slowest of the four GP18 riders.

Dani Pedrosa likewise endured a tough opening session on the second works Honda that left him 17th.

Thomas Luthi was the only other crasher besides Vinales of a relatively incident-free session, losing the front end at the downhill Scarperia right-hander at the halfway point.

FP1 times