Chip Ganassi Racing's Scott Dixon led the way in a red flagged second practice session for the penultimate IndyCar race of the season at Watkins Glen.
Dixon's team-mate, Max Chilton, caused the session to be stopped briefly with 22 minutes to go after slapping the barrier.
Chilton lost control of his car in the second part of the Bus Stop complex, then spun 180 degrees before hitting the wall on his right-hand side.
Five minutes were added to the session but nobody could beat Dixon's 1m22.617s, set on the prime tyre early in the session.
Penske's Will Power finished just under a tenth off Dixon with a 1m22.7129s. It was a much more promising session for Power, who languished in 15th place in first practice.
Graham Rahal was third fastest after topping the first practice session, ending up just ahead of reigning champion Simon Pagenaud.
Fifth went to the Andretti Autosport machine driven by Alexander Rossi, buoyed by his multi-year contract extension with the team.
Penske's Helio Castroneves finished sixth despite brushing one of the barriers late in the session.
Charlie Kimball was seventh after missing most of first practice because of an electronics failure.
Andretti Autosport team-mates Ryan Hunter-Reay and Takuma Sato were eighth and ninth, with championship leader Josef Newgarden rounding out the top 10 for Penske.
Jack Harvey, on his first outing for Schmidt Peterson Motorsports, outpaced team-mate James Hinchcliffe in 18th.
|1||Scott Dixon||Chip Ganassi Racing||Dallara/Honda||1m22.6187s||-||14|
|2||Will Power||Team Penske||Dallara/Chevrolet||1m22.7129s||0.0942s||19|
|3||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||1m22.9716s||0.3529s||22|
|4||Simon Pagenaud||Team Penske||Dallara/Chevrolet||1m23.0915s||0.4728s||19|
|5||Alexander Rossi||Andretti Herta||Dallara/Honda||1m23.1124s||0.4937s||21|
|6||Helio Castroneves||Team Penske||Dallara/Chevrolet||1m23.2760s||0.6573s||16|
|7||Charlie Kimball||Chip Ganassi Racing||Dallara/Honda||1m23.3871s||0.7684s||22|
|8||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||1m23.4683s||0.8496s||20|
|9||Takuma Sato||Andretti Autosport||Dallara/Honda||1m23.5152s||0.8965s||22|
|10||Josef Newgarden||Team Penske||Dallara/Chevrolet||1m23.5842s||0.9655s||22|
|11||Tony Kanaan||Chip Ganassi Racing||Dallara/Honda||1m23.7672s||1.1485s||22|
|12||Sebastien Bourdais||Dale Coyne Racing||Dallara/Honda||1m23.7769s||1.1582s||20|
|13||Conor Daly||AJ Foyt Enterprises||Dallara/Chevrolet||1m23.8158s||1.1971s||19|
|14||Carlos Munoz||AJ Foyt Enterprises||Dallara/Chevrolet||1m23.8752s||1.2565s||19|
|15||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||1m23.8922s||1.2735s||23|
|16||Marco Andretti||Andretti Autosport||Dallara/Honda||1m23.9071s||1.2884s||22|
|17||Max Chilton||Chip Ganassi Racing||Dallara/Honda||1m24.2403s||1.6216s||8|
|18||Jack Harvey||Schmidt Peterson Motorsports||Dallara/Honda||1m24.3972s||1.7785s||24|
|19||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||1m24.4012s||1.7825s||17|
|20||J.R. Hildebrand||Ed Carpenter Racing||Dallara/Chevrolet||1m24.4578s||1.8391s||23|
|21||Ed Jones||Dale Coyne Racing||Dallara/Honda||1m24.6153s||1.9966s||22|