Andrea Dovizioso was able to complete just two laps on the first day of Ducati's private test at Jerez on Wednesday due to the recurrence of a neck injury.
The Italian had joined new team-mate Nicky Hayden and Pramac satellite riders Andrea Iannone and Michele Pirro - standing in for the injured Ben Spies - at the Spanish circuit.
He was forced to call an early halt to proceedings due to neck pain however, spending the rest of the day in a neck brace.
Ducati team boss Vittoriano Guareschi said Dovizioso's injury had first started when he competed in the recent Monza Rally.
"Andrea felt some pain during the Monza Rally. He went to the osteopath and it seemed it was nothing. Instead, as soon as he got onto the track, he had to stop," Guareschi told Gazzetta dello Sport.
Hayden finished fastest of Ducati's four riders, clocking a 1m40.855s. Pirro was just over one second slower in second, fractions ahead of Iannone. Avintia's new line-up of Hiroshi Aoyama and Hector Barbera were also present.
Speaking on Wednesday, Guareschi said that Hayden had tested new parts in a bid to help Ducati settle on a future direction.
"For one reason or another we haven't made progress in testing since mid-season," he admitted.
"Nicky has focused on a new chassis, and will test the swingarm. We'd like to know whether we can count on these new parts."
The three day test concludes on Friday.