At his home circuit, Rossi seized control of the timesheets in the closing stages with a succession of quick laptimes, the last of which put him 0.136s clear of nearest challenger Pol Espargaro.

The Spaniard has been a factor near the top all session, setting the quickest time with 12 minutes remaining aboard the satellite Tech 3 Yamaha with a 1m33.642s.

That remained the benchmark until Rossi set a 1m33.605s on the works machine, which the seven-time premier class champion swiftly followed up with a 1m33.523s and then a 1m33.451s on his last flying lap.

Espargaro improved to a 1m33.587s late on, ensuring a Yamaha one-two.

Silverstone race winner Maverick Vinales was third quickest on the Suzuki, 0.262s behind Rossi, with the Honda of Marc Marquez only a further 0.018s back in fourth.

Marquez suffered a low-speed front-end crash at Turn 10 midway through the session, but was soon able to get going again with assistance from the marshals.

Completing the top five was Jorge Lorenzo on the second factory Yamaha, 0.323s off the pace, followed by Marquez's Repsol Honda teammate Dani Pedrosa.

Andrea Dovizioso was Ducati's best representative in seventh place, but the session was a short-lived one for his teammate Andrea Iannone, who had a high-speed crash at Turn 15.

While the Italian had originally seemed to survive unscathed, he was later taken to the medical centre for an x-ray examination and did not reappear for the rest of the session.

Completing the top 10 were Hector Barbera (Avintia Ducati), Cal Crutchlow (LCR Honda) and Scott Redding, whose Pramac Ducati expired in a cloud of smoke after the chequered flag.

Besides Marquez and Iannone, Eugene Laverty (Aspar Ducati), Tito Rabat (Marc VDS Honda) and Danilo Petrucci (Pramac Ducati) all had falls of their own, albeit none of them causing injury.

Of the wildcards and replacements, Michele Pirro was 14th on the third factory Ducati, Alex Lowes was 18th on the second Tech 3 bike (replacing the injured Bradley Smith), and Xavi Fores (who stands in for Loris Baz) completed his first ever MotoGP session 22nd and last on the Avintia Ducati, 3.6s off the pace.

UPDATE: Ducati has confirmed that Iannone has been taken to hospital in nearby Cesena for additional checks for suspected microfractures to his T2 and T3 vertebrae.

First practice times:

Cla	#	Driver	Bike	Time	Gap
1	46	Valentino Rossi	Yamaha	1'33.451
2	44	Pol Espargaro	Yamaha	1'33.587	0.136
3	25	Maverick Viñales	Suzuki	1'33.713	0.262
4	93	Marc Marquez	Honda	1'33.729	0.278
5	99	Jorge Lorenzo	Yamaha	1'33.774	0.323
6	26	Dani Pedrosa	Honda	1'33.786	0.335
7	4	Andrea Dovizioso	Ducati	1'33.863	0.412
8	8	Hector Barbera	Ducati	1'33.882	0.431
9	35	Cal Crutchlow	Honda	1'33.920	0.469
10	45	Scott Redding	Ducati	1'34.034	0.583
11	41	Aleix Espargaro	Suzuki	1'34.072	0.621
12	6	Stefan Bradl	Aprilia	1'34.126	0.675
13	43	Jack Miller	Honda	1'34.143	0.692
14	51	Michele Pirro	Ducati	1'34.234	0.783
15	9	Danilo Petrucci	Ducati	1'34.412	0.961
16	19	Alvaro Bautista	Aprilia	1'34.496	1.045
17	29	Andrea Iannone	Ducati	1'34.699	1.248
18	22	Alex Lowes	Yamaha	1'34.923	1.472
19	68	Yonny Hernandez	Ducati	1'34.925	1.474
20	50	Eugene Laverty	Ducati	1'35.280	1.829
21	53	Tito Rabat	Honda	1'35.302	1.851
22	12	Xavi Fores	Ducati	1'37.090	3.639