Chip Ganassi Racing driver Tony Kanaan put in the quickest time in final practice for IndyCar's return to the famous Road America circuit in Wisconsin.
The Brazilian driver put in a 1m42.658 on his final lap top move to the top of the timesheets in the 45-minute third practice session.
He finished just over one tenth of a second clear of his team-mate and reigning IndyCar champion Scott Dixon, with Penske's Will Power in third place.
Fellow Ganassi driver and Road America rookie Max Chilton was fourth fastest. Friday's practice one pacesetter Simon Pagenaud completed the top five.
Ryan Hunter-Reay and Sebastien Bourdais, who won the last Champ Car race at the track in 2007, were next up.
Late improvements brought Takuma Sato, Alexander Rossi and Helio Castroneves into the top 10 spots.
Conor Daly and Graham Rahal, who was fastest in second practice, were 11th and 12th, ahead of Josef Newgarden.
The Ed Carpenter Racing driver has been granted permission to race after breaking his right clavicle in a crash at the Texas Motor Speedway two weeks ago.
Carlos Munoz lost crucial track time in his Andretti Dallara-Honda after an engine problem in the opening minutes, bringing out a brief red flag.
PRACTICE THREE TIMES
|1||Tony Kanaan||Chip Ganassi Racing||Dallara/Chevrolet||1m42.6580s||-||15|
|2||Scott Dixon||Chip Ganassi Racing||Dallara/Chevrolet||1m42.6693s||0.0113s||16|
|3||Will Power||Team Penske||Dallara/Chevrolet||1m42.8490s||0.1910s||11|
|4||Max Chilton||Chip Ganassi Racing||Dallara/Chevrolet||1m43.0450s||0.3870s||13|
|5||Simon Pagenaud||Team Penske||Dallara/Chevrolet||1m43.0973s||0.4393s||9|
|6||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||1m43.1284s||0.4704s||9|
|7||Sebastien Bourdais||KVSH Racing||Dallara/Chevrolet||1m43.1868s||0.5288s||11|
|8||Takuma Sato||AJ Foyt Enterprises||Dallara/Honda||1m43.2380s||0.5800s||8|
|9||Alexander Rossi||Andretti Herta||Dallara/Honda||1m43.2770s||0.6190s||13|
|10||Helio Castroneves||Team Penske||Dallara/Chevrolet||1m43.3107s||0.6527s||8|
|11||Conor Daly||Dale Coyne Racing||Dallara/Honda||1m43.3502s||0.6922s||13|
|12||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||1m43.4181s||0.7601s||13|
|13||Josef Newgarden||Ed Carpenter Racing||Dallara/Chevrolet||1m43.4366s||0.7786s||9|
|14||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||1m43.4454s||0.7874s||12|
|15||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||1m43.4580s||0.8000s||10|
|16||Mikhail Aleshin||Schmidt Peterson Motorsports||Dallara/Honda||1m43.7530s||1.0950s||12|
|17||Jack Hawksworth||AJ Foyt Enterprises||Dallara/Honda||1m43.8337s||1.1757s||9|
|18||Marco Andretti||Andretti Autosport||Dallara/Honda||1m43.8604s||1.2024s||6|
|19||Charlie Kimball||Chip Ganassi Racing||Dallara/Chevrolet||1m44.1460s||1.4880s||14|
|20||Gabby Chaves||Dale Coyne Racing||Dallara/Honda||1m44.2232s||1.5652s||12|
|21||Juan Pablo Montoya||Team Penske||Dallara/Chevrolet||1m44.4451s||1.7871s||7|
|22||Carlos Munoz||Andretti Autosport||Dallara/Honda||1m47.6205s||4.9625s||1|