Graham Rahal led a Honda 1-2-3-4-5 in opening practice for the penultimate IndyCar Series round at Watkins Glen.
The Rahal Letterman Lanigan driver posted a 1m23.2626s lap to go to the top of the timesheets with seconds to go, displacing Andretti Autosport's Alexander Rossi by just over two tenths of a second.
Rossi, whose contract extension with Andretti was announced at the start of the day, led the way for much of a 45-minute session initially delayed for 10 minutes due to clean-up from incidents in a support series session.
He even having a quick off at the Bus Stop that left his car undamaged.
Chip Ganassi team-mates Max Chilton and Scott Dixon finished third and fourth, with Dixon looking to keep his championship hopes alive at a track he has won on four times previously.
James Hinchcliffe jumped into the top five in the last few minutes, just ahead of Spencer Pigot. Seventh was Ryan Hunter-Reay despite a spin on the exit of the Turn 8 right-hander.
Championship leader Josef Newgarden languished down in eighth place, followed by his Penske team-mates Simon Pagenaud and Helio Castroneves.
Series returnee Jack Harvey, replacing Sebastian Saavedra at Schmidt Peterson Motorsports for the penultimate two rounds, was 20th quickest.
Charlie Kimball rounded off the 21 runners after suffering a mechanical issue with his Ganassi machine that left him with just 65% throttle. He completed only two laps.
|1||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||1m23.2603s||-||19|
|2||Alexander Rossi||Andretti Herta||Dallara/Honda||1m23.4686s||0.2083s||14|
|3||Max Chilton||Chip Ganassi Racing||Dallara/Honda||1m23.5154s||0.2551s||18|
|4||Scott Dixon||Chip Ganassi Racing||Dallara/Honda||1m23.5485s||0.2882s||15|
|5||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||1m23.7734s||0.5131s||12|
|6||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||1m23.8425s||0.5822s||16|
|7||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||1m23.8439s||0.5836s||14|
|8||Marco Andretti||Andretti Autosport||Dallara/Honda||1m23.8742s||0.6139s||16|
|9||Josef Newgarden||Team Penske||Dallara/Chevrolet||1m23.8748s||0.6145s||14|
|10||Simon Pagenaud||Team Penske||Dallara/Chevrolet||1m23.9941s||0.7338s||14|
|11||Helio Castroneves||Team Penske||Dallara/Chevrolet||1m23.9984s||0.7381s||15|
|12||Carlos Munoz||AJ Foyt Enterprises||Dallara/Chevrolet||1m24.0889s||0.8286s||15|
|13||Sebastien Bourdais||Dale Coyne Racing||Dallara/Honda||1m24.2050s||0.9447s||15|
|14||Ed Jones||Dale Coyne Racing||Dallara/Honda||1m24.4073s||1.1470s||15|
|15||Tony Kanaan||Chip Ganassi Racing||Dallara/Honda||1m24.5239s||1.2636s||14|
|16||Will Power||Team Penske||Dallara/Chevrolet||1m24.5499s||1.2896s||15|
|17||Takuma Sato||Andretti Autosport||Dallara/Honda||1m24.6339s||1.3736s||13|
|18||J.R. Hildebrand||Ed Carpenter Racing||Dallara/Chevrolet||1m25.1698s||1.9095s||17|
|19||Conor Daly||AJ Foyt Enterprises||Dallara/Chevrolet||1m25.2532s||1.9929s||15|
|20||Jack Harvey||Schmidt Peterson Motorsports||Dallara/Honda||1m25.5645s||2.3042s||20|
|21||Charlie Kimball||Chip Ganassi Racing||Dallara/Honda||6m44.2572s||5m20.9969s||2|