Casey Stoner led the way during first free practice for the Indianapolis MotoGP, during a session briefly red flagged after a highside for Hector Barbera.
After a two weekend summer break, MotoGP action resumed in dry and bright conditions, albeit on a track still damp in places after heavy overnight rain.
Those patches, and the lack of track use on the infield section, meant grip levels were low and reigning champion Stoner's best time - set on his 13th of 14 laps - was three seconds off his own official circuit best.
Repsol Honda team-mate Dani Pedrosa
also spent substantial time on top of the standings and finished the session just 0.181s from Stoner, with Ducati's Nicky Hayden
snatching third (+0.547s) on his final lap.
Fellow American Ben Spies was the top Yamaha rider in fourth (+0.611s) at a circuit where he has been on the rostrum for the past two seasons.
Honda LCR rookie Stefan Bradl made a quick start to the session before being pushed back to fifth (+1.102s) with fellow satellite RCV rider Alvaro Bautista taking sixth for Gresini.
Cal Crutchlow fell from his Tech 3 Yamaha early in the session after an unseen incident, before returning to take seventh, with Yamaha's world championship leader Jorge Lorenzo
just eighth and 1.387s off the pace of Stoner.
The poor track conditions mean the Spaniard is unlikely to be alarmed. Lorenzo holds a 23 point lead over Pedrosa and 32 point advantage over Stoner.
Valentino Rossi, riding in his first event since announcing a return to Yamaha for 2013, steered his Ducati to ninth place (+1.420s) with Barbera credited with tenth despite his end-of-session absence.