Ryan Hunter-Reay put his Andretti Autosport Dallara-Honda on top in second practice for the IndyCar season finale at Laguna Seca.
All but two entries ran the softer red-sidewalled Firestone tyre compound to set their best times, and it was Andretti Autosport driver Hunter-Reay who clipped 0.02 seconds from Felix Rosenqvist's Chip Ganassi Racing entry to edge to the top with a 1n09.9105s lap of the 2.238-mile course.
Behind Rosenqvist, morning pacesetter Colton Herta put his Harding Steinbrenner Racing Dallara-Honda into third, while Penske's Simon Pagenaud was top title contender in fourth, bouncing back from an off into the Turn 1 gravel that he was able to extricate himself from.
Less lucky was Scott Dixon in the second Ganassi car, who simultaneously spun off at the penultimate and caused a red flag - the subsequent penalty costing him the last five minutes of the session.
How the title can be won
As it stands, Newgarden leads Rossi by 41 points, Penske team-mate and 2016 champion Simon Pagenaud by 42 points, and defending champion Scott Dixon by 85 points.
For Newgarden, the title can be wrapped up by finishing fourth or better as even if Rossi wins and scores all bonus points, as he would be unable to make up sufficient ground.
Even fifth could be enough for Newgarden, but only if Rossi and Simon Pagenaud fail to clinch any bonus points alongside victory at Laguna Seca.
A sixth title for Scott Dixon is looking very unlikely as he would require victory and a full set of bonus points, Newgarden finishing 23rd in a 24-car field, as well as Rossi and Pagenaud finishing sixth or worse.
Santino Ferrucci was fifth, just ahead of points leader Josef Newgarden in the second fastest Penske, while Will Power was seventh after a mild off at the last turn when attempting a second qualifying simulation.
Max Chilton in the second Carlin car and title contender Alexander Rossi stayed on the harder Firestone tyres for that session, ending up 15th and 23rd respectively.
The second part of the session, the so-called warm-up and pitstop practice, featured two red flags caused by Ed Jones and Herta failing to negotiate the first left-hander of the exceedingly tight pitlane entrance and stalling.
By leaving his fresh set of reds until this second part of the session, Rossi was easily able to emerge on top with a time eight tenths faster than his nearest opposition - team-mate Hunter-Reay.
Several teams minimised their pitstop practice in order to try to maximise their time on red tyres to check their duration.
Power ran 18 laps and saw a two-second drop-off, while team-mate Pagenaud also looked very strong across his albeit shorter red-tyre stint.
Rossi shut his engine down as he exited the Corkscrew on his final lap, as he had run out of fuel. He admitted to the media later it was simply to save the fuel pumps, but the car was able to coast from Turn 8A down the hill, negotiate pitlane entry and still reach his pitbox, albeit at painfully slow pace by the end.
Sebastien Bourdais' Dale Coyne Racing with Vasser-Sullivan car did not take part in this 'warm-up' session due to neck pains that prompted a visit to IndyCar medical.
Practice two times
|1||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||1m09.9105s||-||13|
|2||Felix Rosenqvist||Chip Ganassi Racing||Dallara/Honda||1m09.9305s||0.0200s||15|
|3||Colton Herta||Harding Racing||Dallara/Honda||1m09.9317s||0.0212s||14|
|4||Simon Pagenaud||Team Penske||Dallara/Chevrolet||1m10.1353s||0.2248s||11|
|5||Santino Ferrucci||Dale Coyne Racing||Dallara/Honda||1m10.2066s||0.2961s||6|
|6||Josef Newgarden||Team Penske||Dallara/Chevrolet||1m10.2248s||0.3143s||14|
|7||Scott Dixon||Chip Ganassi Racing||Dallara/Honda||1m10.2722s||0.3617s||10|
|8||Will Power||Team Penske||Dallara/Chevrolet||1m10.3350s||0.4245s||13|
|9||Marcus Ericsson||Schmidt Peterson Motorsports||Dallara/Honda||1m10.3910s||0.4805s||12|
|11||Marco Andretti||Andretti Herta||Dallara/Honda||1m10.4426s||0.5321s||14|
|12||Takuma Sato||Rahal Letterman Lanigan||Dallara/Honda||1m10.4468s||0.5363s||16|
|13||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||1m10.4632s||0.5527s||14|
|14||Conor Daly||Andretti Autosport||Dallara/Honda||1m10.4633s||0.5528s||16|
|16||Zach Veach||Andretti Autosport||Dallara/Honda||1m10.6620s||0.7515s||15|
|17||Matheus Leist||AJ Foyt Enterprises||Dallara/Chevrolet||1m10.7009s||0.7904s||10|
|18||Sebastien Bourdais||Dale Coyne Racing||Dallara/Honda||1m10.7061s||0.7956s||10|
|19||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||1m10.7730s||0.8625s||13|
|20||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||1m10.8807s||0.9702s||19|
|21||Ed Jones||Ed Carpenter Racing||Dallara/Chevrolet||1m10.8846s||0.9741s||13|
|22||Tony Kanaan||AJ Foyt Enterprises||Dallara/Chevrolet||1m10.9484s||1.0379s||13|
|23||Alexander Rossi||Andretti Autosport||Dallara/Honda||1m11.0234s||1.1129s||13|
|24||Jack Harvey||Meyer Shank Racing||Dallara/Honda||1m11.0584s||1.1479s||14|
|1||Alexander Rossi||Andretti Autosport||Dallara/Honda||1m10.0988s||-||11|
|2||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||1m10.8926s||0.7938s||14|
|3||Colton Herta||Harding Racing||Dallara/Honda||1m10.8950s||0.7962s||11|
|4||Scott Dixon||Chip Ganassi Racing||Dallara/Honda||1m11.0371s||0.9383s||14|
|5||Conor Daly||Andretti Autosport||Dallara/Honda||1m11.1182s||1.0194s||12|
|6||Simon Pagenaud||Team Penske||Dallara/Chevrolet||1m11.6939s||1.5951s||18|
|7||Takuma Sato||Rahal Letterman Lanigan||Dallara/Honda||1m11.8590s||1.7602s||19|
|9||Felix Rosenqvist||Chip Ganassi Racing||Dallara/Honda||1m11.9168s||1.8180s||18|
|10||Matheus Leist||AJ Foyt Enterprises||Dallara/Chevrolet||1m12.1161s||2.0173s||18|
|11||Marco Andretti||Andretti Herta||Dallara/Honda||1m12.1296s||2.0308s||14|
|12||Ed Jones||Ed Carpenter Racing||Dallara/Chevrolet||1m12.1402s||2.0414s||14|
|14||Zach Veach||Andretti Autosport||Dallara/Honda||1m12.4342s||2.3354s||17|
|15||Marcus Ericsson||Schmidt Peterson Motorsports||Dallara/Honda||1m12.5036s||2.4048s||19|
|16||Josef Newgarden||Team Penske||Dallara/Chevrolet||1m12.6557s||2.5569s||19|
|17||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||1m12.6597s||2.5609s||14|
|18||Will Power||Team Penske||Dallara/Chevrolet||1m12.6807s||2.5819s||19|
|19||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||1m12.7008s||2.6020s||14|
|20||Jack Harvey||Meyer Shank Racing||Dallara/Honda||1m12.8349s||2.7361s||19|
|21||Santino Ferrucci||Dale Coyne Racing||Dallara/Honda||1m13.0335s||2.9347s||18|
|22||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||1m13.3935s||3.2947s||16|
|23||Tony Kanaan||AJ Foyt Enterprises||Dallara/Chevrolet||1m13.4652s||3.3664s||14|