Casey Stoner took a new Ohlins front fork to the top of the Friday practice timesheets for the Indianapolis MotoGP, but isn't sure if the new development made the difference.
The Ducati rider has battle front end problems for most of the season, even switching back to last year's Ohlin design, but after testing some 2011 forks at Brno the Australian decided to run them at Indy.
Stoner finished free practice with a 0.225sec advantage over MotoGP title leader Jorge Lorenzo.
"We tried the new front fork today that we tested in Brno and it felt good, although this is not the kind of circuit where you can really push so it's hard to say if it improved the package," explained Stoner.
Stoner has only ridden at Indianapolis once before, in the inaugural 2008 event, having skipped last year's round whilst seeking a cure for fatigue problems.
"For the first two laps I didn't remember anything about the track from two years ago but after that it all came back pretty quickly!" he said. "This is quite a unique circuit because of the different types of surface and the amount of bumps out there so we had to improvise a little today because it's not easy to pick the right line.
"We made a good start but I'm sure everybody will work things out better tomorrow and close the gap. Having said that this is a good situation to be in on the first day and for the first time in a while we feel there is potential to improve."
Team-mate Nicky Hayden was third fastest.