Casey Stoner upheld Ducati home honour with a close third place in Friday practice at Mugello, but the three other Desmosedicis were left at the tail end of the field.
Stoner, second to Valentino Rossi in last year's Italian Grand Prix, made several appearances at the top of the timesheets on his way to third place behind championship leader Jorge Lorenzo and the Spaniard's Fiat Yamaha team-mate Rossi.
The Australian was just 0.079sec behind Rossi - winner of the event for the last seven years - and only 0.274sec from Lorenzo.
Stoner used the session to run back-to-back tests between the carbon-fibre swingarm that he has used since the start of the season with the previous aluminium version.
“The idea behind going back to the aluminium swingarm is just in order to see where we can improve more with the carbon version,” said the 2007 world champion, who will start Sunday's race level on points with Rossi and just one point behind Lorenzo.
“The carbon swingarm is better in a lot of ways but there is one area we're struggling to find grip with in the turns. So we're using the aluminium one to find out where it is better and why, and then hopefully transfer that across.
“I don't mind riding with one of each because we can do similar lap times so it's not a problem. The only way it affected us today was that we had to make a lot of short runs and do a lot of testing but we're happy with the way things went.
“Today was a case of spending a time learning more about our bike rather than setting it up to race, which we'll focus on tomorrow. Considering how close we are to the top, I think we can be quite confident,” he revealed.
The second best GP9 on Friday was that of rookie Niccolo Canepa, who used his test knowledge of the track to claim 14th place at the start of his first home grand prix, with a best lap time 2.175sec slower than Stoner.