Andretti's Ryan Hunter-Reay topped the times in the second practice session ahead of the 2018 IndyCar season-opener at St Petersburg.
Hunter-Reay took the top spot midway through the running and engaged in place swapping with Penske's Will Power for the benchmark time.
But with just over 15 minutes to go, Hunter-Reay took command of the session with a time of 1m00.8295s.
Schmidt Peterson Motorsports driver James Hinchcliffe nipped ahead of Power for second place a few minutes with the Australian running on the slower black-compound tyres.
Despite teams using the more representative session to do qualifying simulations, there was little movement in the top 10 in the remaining final minutes.
Chip Ganassi Racing's Scott Dixon was one of the few to do so, going fourth in the final minute.
Dixon was also one of several drivers to be caught out at the quick left-right of Turns 3 and 4, spinning onto the escape road.
The new 2018 universal aerokit has increased braking zones and removed a high amount of downforce, meaning that the usually difficult Turn 1 at the end of the runway was usurped by the third and fourth corners as the trickiest part of the lap.
Reigning IndyCar champion Josef Newgarden improved in the second session to go fifth ahead of Andretti's Alexander Rossi.
Robert Wickens continued a so far impressive IndyCar debut weekend by going seventh for SPM.
Dale Coyne Racing's Sebastien Bourdais beat Tony Kanaan and AJ Foyt Racing to eighth.
New Rahal Letterman Lanigan Racing recruit Takuma Sato improved in the second session to be 10th ahead of Marco Andretti and first practice pacesetter Matheus Leist.
Penske's Simon Pagenaud made a mistake late in the session at the exit of Turn 4, clipping the wall and nursing his car back to the pits with a time good enough for 13th.
Jordan King also made a similar error on his way to 15th, causing one of two red flags, and finished one place behind Ed Carpenter Racing team-mate Spencer Pigot.
The other red flag was caused by Rene Binder on his debut weekend for Juncos Racing, hitting the wall on the exit of Turn 4 after a high-speed spin that somehow left him without major damage to his car.
|1||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||1m00.8295s||12|
|2||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||0.0429s||20|
|3||Will Power||Team Penske||Dallara/Chevrolet||0.1638s||16|
|4||Scott Dixon||Chip Ganassi Racing||Dallara/Honda||0.2709s||20|
|5||Josef Newgarden||Team Penske||Dallara/Chevrolet||0.2717s||19|
|6||Alexander Rossi||Andretti Autosport||Dallara/Honda||0.3247s||17|
|7||Robert Wickens||Schmidt Peterson Motorsports||Dallara/Honda||0.3895s||18|
|8||Sebastien Bourdais||Dale Coyne Racing||Dallara/Honda||0.4446s||13|
|9||Tony Kanaan||AJ Foyt Enterprises||Dallara/Chevrolet||0.4890s||16|
|10||Takuma Sato||Rahal Letterman Lanigan||Dallara/Honda||0.5196s||18|
|11||Marco Andretti||Andretti Herta||Dallara/Honda||0.5485s||12|
|12||Matheus Leist||AJ Foyt Enterprises||Dallara/Chevrolet||0.6090s||20|
|13||Simon Pagenaud||Team Penske||Dallara/Chevrolet||0.6214s||10|
|14||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||0.7210s||16|
|15||Jordan King||Ed Carpenter Racing||Dallara/Chevrolet||0.7284s||16|
|16||Ed Jones||Chip Ganassi Racing||Dallara/Honda||0.7524s||20|
|17||Gabby Chaves||Harding Racing||Dallara/Chevrolet||0.7882s||22|
|18||Zach Veach||Andretti Autosport||Dallara/Honda||1.0128s||16|
|20||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||1.1698s||17|
|21||Zachary Claman||Dale Coyne Racing||Dallara/Honda||1.2073s||19|
|23||Jack Harvey||Michael Shank Racing||Dallara/Honda||1.3345s||18|
|24||Rene Binder||Juncos Racing||Dallara/Chevrolet||1.4959s||19|