Repsol Honda's Marc Marquez was fastest in this morning's opening MotoGP free practice session at Mugello but had to wait until the final minutes before the track was dry enough for slicks to work properly.
Overnight rain had dampened the circuit and low temperatures and a lack of wind meant it didn't dry very quickly. Danilo Petrucci was the first rider out on slicks, followed by PBM's Yonny Hernandez who put in the first meaningful times, posting a 1'59.194 and then a 1'58.776.
The Columbian's times signalled the rest of the pack, bar Jorge Lorenzo, to switch to the dry Bridgestones and Marquez made the most of the opportunity, going top with a 1'56.506 with LCR Honda's Stefan Bradl in second, a second in arrears.
Ducati test rider Michele Pirro then hit the front on a 1'56.106 as factory team-mate Andrea Dovizioso lost the front into San Donato before Marquez then assumed control with a 1'54.792. The young Spaniard then ran across the gravel trap at Materassi but kept it upright until he hit the wet grass and toppled over.
Pirro remained in second place but lowered his time to a 1'55.195 to stay ahead of Bradl while CRT man Karel Abraham leapt into fourth with his last lap of the session on a 1'55.874 with Hernandez in fifth.
Monster Yamaha's Bradley Smith was the next best of the prototypes in sixth, followed by Nicky Hayden, Dan Pedrosa, Cal Crutchlow and Ben Spies. Jorge Lorenzo's lap in the wet was enough for 14th place while Valentino Rossi, who ran into the gravel in front of the Ducati grandstand, ended in 19th. Michael Laverty's first run out on the Mugello circuit left him without a qualifying time but he is not alone.