Ducati is pondering swapping from the Factory class to the new Open category, which has replaced CRT this year.
The Open division was originally intended for privateer entrants.
Participants must use spec ECUs and software, but get an extra four litres of fuel per race, softer tyres and can use 12 engines per season rather than five, with engine development also allowed.
Dovizioso was fifth quickest in the session, though Ducati did not reveal which specification he was using for his best lap.
The Italian remained non-committal about the Open Ducati's performance.
"There are a few different controls with it and it obviously doesn't work as well as our Factory software, but tomorrow we'll do some more tests," he said.
The Open class has already attracted controversy due to the pace of Forward Racing's Yamaha-based machine, which has challenged for outright fastest times with Aleix Espargaro.
The bike's speed has angered Honda, which believes its own Open machine - being used by Aspar, Cardion and Gresini's Scott Redding - is closer to the intended spirit of the regulations.
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