Casey Stoner, winless so far in 2010, got the better of title leader Jorge Lorenzo during Friday practice for this weekend's Indianapolis MotoGP round.
The Ducati rider lapped the infield circuit in a time of 1min 40.884sec, which proved 0.225sec faster than Fiat Yamaha star Lorenzo, who was the only rider within half a second of Stoner.
Stoner's team-mate Nicky Hayden began his home event with a promising third place in practice, but also suffered a high-speed fall at turn 13 that threatened to have cause further harm to his recently chipped left wrist.
Fortunately, Hayden was able to get back out on track and doesn't seem to have aggravated the injury. Hayden, who took his only Ducati podium to date at Indy last year, finished the session 0.521sec from Stoner.
Hayden wasn't the only home rider to tumble during the session with rookie Ben Spies suffering a similar lowside fall, at turn six, with six minutes to go.
The Monster Yamaha Tech 3 rider, who will switch to the factory Yamaha team next season, was also unhurt, but dropped from sixth to eighth.
Those that jumped ahead of Spies in the closing minutes were Italians Valentino Rossi and Andrea Dovizioso.
Rossi, like team-mate Lorenzo, was riding in the special Fiat 500 livery first seen at Laguna Seca - featuring hundreds of fans' faces - but struggled for much of the session before jumping from ninth to fifth on his very last lap.
Dovizioso meanwhile moved into a more modest seventh as Repsol Honda team-mate Dani Pedrosa, on pole at Indy last year and leader of the race until he fell, once again led the RCV challenge in fourth.
Colin Edwards enjoyed one of his best starts to a 201 race weekend with sixth in front of his home fans on the second Tech 3 bike, with Pramac Ducati's Aleix Espargaro behind Spies in ninth and Gresini Honda's Marco Melandri in tenth.