Lorenzo surged ahead of pole sitter Valentino Rossi into the first turn at the Mugello circuit and quickly established a comfortable lead.

Andrea Dovizioso, Lorenzo's Ducati teammate, finished second, more than six seconds behind, and Rossi crossed third, just behind Dovizioso.

Championship leader Marc Marquez had just passed Rossi for second when he lost control of his bike and ended up on the dirt four laps into the 23-lap race. Marquez finished 16th.

Still, Marquez leads Rossi by 23 points, with Maverick Vinales third, 28 points back.

Vinales finished eighth.

Miguel Oliveira won the Moto2 race and Jorge Martin won the Moto3 race.