Simon Pagenaud topped the times in an incident-laded final practice IndyCar session ahead of qualifying on the streets of Baltimore.
Schmidt driver Pagenaud moved to the top on his final lap with a time of 1m18.4391s to displace Scott Dixon by 0.1s.
Will Power was third-fastest; his time just 0.03s down on Dixon's.
The pair had earlier been responsible for one of the three stoppages during the session when Dixon backed off to try to create some space for himself, only for the closely-following Power to tag the rear of his Ganassi car.
Dixon spun into the wall, breaking his front wing, before stopping in the middle of the track, while Power was able to return to the Penske pits to have his own broken wing attended to.
Simona de Silvestro also triggered a red with her trip into the tyre barrier at Turn 8, while championship leader Helio Castroneves caused the first when he had to be rescued from an escape road on his first lap.
There was also plenty of action at the chicane, with several drivers being launched skyward after taking too much of the kerb at the exit.
James Hinchcliffe and Marco Andretti both suffered minor damage from glancing the outside wall upon landing, and a handful of others were lucky to escape the same fate.
Pos Driver Team/Engine Time Gap 1. Simon Pagenaud Schmidt/Honda 1m18.4391s 2. Scott Dixon Ganassi/Honda 1m18.5486s +0.1095s 3. Will Power Penske/Chevy 1m18.5826s +0.1435s 4. Sebastien Bourdais Dragon/Chevy 1m18.6597s +0.2206s 5. James Jakes Rahal/Honda 1m18.7980s +0.3589s 6. Graham Rahal Rahal/Honda 1m18.9363s +0.4972s 7. Oriol Servia Panther/Chevy 1m18.9590s +0.5199s 8. EJ Viso Andretti/Chevy 1m18.9834s +0.5443s 9. Luca Filippi Herta/Honda 1m19.0194s +0.5803s 10. Justin Wilson Coyne/Honda 1m19.0563s +0.6172s 11. Helio Castroneves Penske/Chevy 1m19.0648s +0.6257s 12. Josef Newgarden Fisher/Honda 1m19.0894s +0.6503s 13. Dario Franchitti Ganassi/Honda 1m19.1284s +0.6893s 14. Tristan Vautier Schmidt/Honda 1m19.1649s +0.7258s 15. Charlie Kimball Ganassi/Honda 1m19.2145s +0.7754s 16. Ryan Hunter-Reay Andretti/Chevy 1m19.2340s +0.7949s 17. Sebastian Saavedra Dragon/Chevy 1m19.4357s +0.9966s 18. James Hinchcliffe Andretti/Chevy 1m19.4538s +1.0147s 19. Tony Kanaan KV/Chevy 1m19.4868s +1.0477s 20. Marco Andretti Andretti/Chevy 1m20.0122s +1.5731s 21. Takuma Sato Foyt/Honda 1m20.0539s +1.6148s 22. Simona de Silvestro KV/Chevy 1m20.1658s +1.7267s 23. Ed Carpenter Carpenter/Chevy 1m21.1120s +2.6729s 24. Stefan Wilson Coyne/Honda 1m21.1770s +2.7379s