Triple MotoGP champion made his Ducati MotoGP debut during the start of post-season testing at Valencia on Tuesday morning.
The Spaniard, a Yamaha rider since his 2008 premier-class debut, is the most high-profile rider to join Ducati since former team-mate Valentino Rossi in 2011.
Lorenzo won four races this season on his way to third in the championship, while Ducati took its first race victories since 2010 courtesy of a win each for Andrea Iannone and Andrea Dovizioso.
Yamaha has given Lorenzo permission to test for Ducati at Valencia, but not at a private Jerez test later this month. After Wednesday, Lorenzo will thus have to wait until Sepang at the end of January for his next Desmosedici appearance.