Michele Pirro, who has spent his debut MotoGP season on Gresini's CRT specification FTR-Honda, will switch to the role of official Ducati test rider for 2013.
Pirro clinched the deal after testing for Ducati earlier this year, and has no regrets about stepping back from racing.
The 26-year-old Italian told GPOne.com:
"Thinking that if everything goes well you can finish 13th is a frustrating feeling" adding, "I'll do two or three races as a wild-card with the Desmosedici."
Pirro is 15th in the championship standings and the third best CRT behind Aspar Aprilia team-mates Aleix Espargaro and Randy de Puniet. The 2011 Valencia Moto2 race winner has claimed a best finish of ninth place at Assen.
Pirro is expected to join, rather than replace, present Ducati test rider Franco Battaini.