Nicky Hayden got his first taste of Ducati's GP11.1 motorcycle during Friday's practice sessions for his home US MotoGP at Laguna Seca.
The GP11.1 - which combines this year's 800cc engine with next year's (1000cc) chassis and a new seamless transmission gearbox - has been used by team-mate Valentino Rossi for the last three rounds.
However, the bike doesn't seem to offer the clear step forward that Ducati had hoped for, as underlined by the possibility that Rossi would switch back to the normal GP11 this weekend.
Hayden did an initial run with the GP11 before doing a comparison between the two versions and then using only the GP11.1 in the afternoon.
The 2005 and 2006 US GP winner, for Honda, was seventh and tenth in Friday's sessions, which he finished 1.139sec from Yamaha's Jorge Lorenzo.
The Kentuckian is yet to decide which bike to use for the rest of the weekend.
“It's nice to be back at Laguna, a track I love, and things started off okay with the new bike," said Hayden. "It was my first time with it, but it wasn't something I needed a lot of time to get familiar with since I've ridden the GP12, which is similar.
"We're just trying to evaluate it, and it definitely has some pluses. 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. We're just trying to decide which bike will give us the best chance for a good result on Sunday.”
Hayden finished 0.06sec behind the top Ducati rider on Friday, Pramac's Randy de Puniet - in ninth with the GP11.
Rossi, who decided to stick exclusively with the GP11.1, was 0.174sec behind Hayden in eleventh.
“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," explained 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.
"I'm pleased that Bridgestone brought some soft tyres, which worked well in the cool temperatures this morning, although I felt better with the hard when the conditions were warmer in the afternoon. If race conditions are like this, that's what I'll use.”