Josef Newgarden opened the Milwaukee IndyCar weekend by setting the pace in the opening practice session on the one-mile oval.
The Sarah Fisher Hartman driver lapped in 22.0232 seconds at a speed of 165.916mph in his Dallara-Honda at what is the first of the short oval circuits visited by the series this year.
Helio Castroneves was 0.0863s slower in his Penske-run Dallara-Chevrolet, the American-powered machines being outnumbered 6-4 by their Japanese counterparts in the top 10.
KV's EJ Viso was third-quickest, with Bryan Herta driver Alex Tagliani and Panther's JR Hildebrand rounding out the top five.
Last year's Milwaukee winner Dario Franchitti finished up just behind his Ganassi team-mate Scott Dixon with the 11th-best time, while championship leader Will Power was 19th for Penske.
Pos Driver Team/Car Time Gap 1. Josef Newgarden Fisher DW12-Honda 22.0232s 2. Helio Castroneves Penske DW12-Chevy 22.1095s + 0.0863s 3. EJ Viso KV DW12-Chevy 22.2776s + 0.2544s 4. Alex Tagliani Herta DW12-Honda 22.3654s + 0.3422s 5. JR Hildebrand Panther DW12-Chevy 22.3926s + 0.3694s 6. Rubens Barrichello KV DW12-Chevy 22.5160s + 0.4928s 7. James Jakes Coyne DW12-Honda 22.5821s + 0.5589s 8. Graham Rahal Ganassi DW12-Honda 22.6121s + 0.5889s 9. Takuma Sato Rahal DW12-Honda 22.6154s + 0.5922s 10. Scott Dixon Ganassi DW12-Honda 22.6159s + 0.5927s 11. Dario Franchitti Ganassi DW12-Honda 22.6309s + 0.6077s 12. Marco Andretti Andretti DW12-Chevy 22.6325s + 0.6093s 13. Oriol Servia Panther/DRR DW12-Chevy 22.6814s + 0.6582s 14. James Hinchcliffe Andretti DW12-Chevy 22.7178s + 0.6946s 15. Justin Wilson Coyne DW12-Honda 22.7202s + 0.6970s 16. Tony Kanaan KV DW12-Chevy 22.7780s + 0.7548s 17. Ryan Briscoe Penske DW12-Chevy 22.8484s + 0.8252s 18. Ryan Hunter-Reay Andretti DW12-Chevy 22.8690s + 0.8458s 19. Will Power Penske DW12-Chevy 22.8727s + 0.8495s 20. Charlie Kimball Ganassi DW12-Honda 22.9290s + 0.9058s 21. Simon Pagenaud Schmidt DW12-Honda 22.9840s + 0.9608s 22. Mike Conway Foyt DW12-Honda 23.2188s + 1.1956s 23. Katherine Legge Dragon DW12-Chevy 23.2237s + 1.2005s 24. Ed Carpenter Carpenter DW12-Chevy 23.5241s + 1.5009s 25. Simona de Silvestro HVM DW12-Lotus 23.5898s + 1.5666s