Valentino Rossi will stick with the 2012-chassis-based Ducati GP11.1 for the rest of the US MotoGP weekend while team-mate Nikcy Hayden is expected to remain on the old bike having tried both during Friday's free practice sessions at Laguna Seca.
Rossi who was 11th fastest, less than two tenths slower than Hayden - who set that time on the older machine - was happier with the feel of the GP11.1 and remains determined to turn his recent form around.
"After yesterday's technical briefing with Jerry [Burgess] and the team, we decided to continue with the new bike, so I only used the GP11.1," said Rossi. "We started with one bike that had the Sachsenring setup, which has a significant change to the weight distribution, while the second bike had a standard setup. I actually prefer the one from Germany.
"We need to keep working to balance the bike and to improve the rear grip, and then we hope to get a little closer to the pace of the others.
"We have to try to do better than we have at the last couple of races, and especially to start closer to the front."
Hayden, who has won twice at Laguna Seca, is believed to want to ride the GP11 in the race as he feels it will give him the best chance of a strong result in his home race.
The Kentucky rider did however have good things to say about the new bike, which features a new seamless shift gearbox.
"We're just trying to evaluate it, and it definitely has some pluses," said Hayden. "The gearbox is really nice, so Ducati has done a great job with that.
"We're always trying different things like shock springs and new settings, but it's not every day that you get to ride with a new gearbox that probably everybody will have in the future."