After a slippery Friday morning session on the new Indianapolis asphalt, Casey Stoner raised the MotoGP pace by over 2.5sec as conditions improved significantly during the afternoon.
The recently resurfaced infield section, from turns 5 to 16, was heavily criticised this morning, when the slippery new asphalt meant the best lap time was over three-seconds from record pace.
That was set by home star Ben Spies, while the likes of reigning world champion Jorge Lorenzo and 2010 Indy winner Dani Pedrosa - who described the surface as "not what a world championship deserves" - had languished five seconds off the Indy best.
But further running by the Moto2 and 125cc classes between the MotoGP sessions helped extract more grip and Spies' morning best was beaten after just a few minutes of FP2.
Continuous improvements followed before Stoner - second this morning - set his best time of 1min 40.724sec on his 18th and final lap, having narrowly avoided some local wildlife which dashed across the track in front of him a few minutes earlier!
Factory Yamaha rider Spies, runner-up from pole at Indy last year, was just 0.194sec behind the Repsol Honda rider, with Pedrosa 0.481sec from team-mate Stoner in third.
Like Pedrosa, Lorenzo leapt up the order this afternoon to finish fourth, albeit 0.737sec from Stoner - whom Lorenzo trails by 32 points in the championship.
Andrea Dovizioso was fifth, with American Colin Edwards the final rider within one-second of Stoner and the top satellite rider for Monster Yamaha Tech 3.
Marco Simoncelli dropped from fourth to seventh by the end of FP2, while the increase in grip also hurt the factory Ducatis.
Nicky Hayden and Valentino Rossi - fifth and sixth this morning - dropped back to eighth (+1.065sec) and eleventh (+1.681sec) places respectively on their GP11.1s this afternoon.
Between them were Suzuki's Alvaro Bautista and Pramac Ducati's Randy de Puniet, while the tail end of the 17 rider timesheet saw Toni Elias sandwiched between rookies Cal Crutchlow and Karel Abraham.
Friday practice (2):
10. de Puniet