Pramac Ducati rider Danilo Petrucci will skip the two-day post-race MotoGP test at Valencia, and will be replaced at the Italian squad by Michele Pirro.
A brief statement from the satellite Ducati team said that Petrucci had been forced to return home to Italy on Monday for "family reasons", and will therefore miss the tests scheduled for 15-16 November.
Regular Ducati tester Pirro, who substituted for an injured Petrucci for three races early in the season, will take his place for the Valencia test.
Petrucci had been due to test the GP17 Desmosedici bike that he had earned after overcoming Pramac teammate Scott Redding in an eight-round internal championship that began in Brno.
The Italian rider eventually came out on top by 46 points to 28, adjusted after the pair's collision at Aragon that left Redding fuming with Petrucci.
A total of 25 bikes have been entered for the Valencia test, with Suzuki and Aprilia entering an extra bike each for Takuya Tsuda and Eugene Laverty respectively.
During the Valencia Grand Prix weekend, it was confirmed that Laverty - who switches to Aprilia's World Superbike project for 2017 - will remain part of the Italian marque's MotoGP project as a test and replacement rider.
The Irishman contested his final race for the Aspar Ducati team on Sunday in Valencia, finishing out of the points in 16th.