Helio Castroneves ended Friday on top after the second IndyCar practice session at Barber Motorsports Park.
On an afternoon where several drivers enjoyed a stint at the front as the track improved and teams tried different approaches with tyres, Castroneves finished up as the benchmark with a best time of 1m08.5540s.
He is one of three Penske drivers this weekend, as he and Will Power are joined by single-seater returnee AJ Allmendinger.
"Obviously with the stoppage in the end a lot of guys probably put on new tyres, but the car felt pretty good," he said. "With AJ and Will, we've been actually doing a lot of different stuff out there and it seems to be working."
Alex Tagliani was second fastest for Bryan Herta Autosport, just ahead of the morning session's pacesetter Tristan Vautier, the Frenchman's Schmidt team-mate Simon Pagenaud, and Power, who had earlier been the first driver of the weekend to drop into the 1m08s range.
Despite his strong start, Vautier was reluctant to read too much into his early pace.
"I think that I still have some room to keep improving, and we need to carry the momentum from today into tomorrow," he said.
"It's a lot of fun out here, there's a lot of grip and the track was very fast. You can really enjoy the grip that those tyres produce. Especially on fast corners; you can really feel what the cars are capable of."
EJ Viso managed to finish up just behind Scott Dixon with the seventh-best time despite causing a late red flag courtesy of a trip into the gravel at Turn 9, while the encouraging start to Allmendinger's single-seater comeback continued with the Penske racer going eighth fastest.
James Jakes and Takuma Sato completed the top 10.
Pos Driver Team/Car Time Gap 1. Helio Castroneves Penske Dallara-Chevy 1m08.5540s 2. Alex Tagliani Herta Dallara-Honda 1m08.6288s + 0.0748s 3. Tristan Vautier Schmidt Dallara-Honda 1m08.6720s + 0.1180s 4. Simon Pagenaud Schmidt Dallara-Honda 1m08.7627s + 0.2087s 5. Will Power Penske Dallara-Chevy 1m08.8066s + 0.2526s 6. Scott Dixon Ganassi Dallara-Honda 1m08.8446s + 0.2906s 7. EJ Viso Andretti Dallara-Chevy 1m08.8556s + 0.3016s 8. AJ Allmendinger Penske Dallara-Chevy 1m08.9119s + 0.3579s 9. James Jakes Rahal Dallara-Honda 1m08.9479s + 0.3939s 10. Takuma Sato Foyt Dallara-Honda 1m08.9817s + 0.4277s 11. Justin Wilson Coyne Dallara-Honda 1m08.9917s + 0.4377s 12. Ryan Hunter-Reay Andretti Dallara-Chevy 1m09.0524s + 0.4984s 13. Oriol Servia Panther/DRR Dallara-Chevy 1m09.1384s + 0.5844s 14. Dario Franchitti Ganassi Dallara-Honda 1m09.1942s + 0.6402s 15. James Hinchcliffe Andretti Dallara-Chevy 1m09.2602s + 0.7062s 16. Tony Kanaan KV Dallara-Chevy 1m09.2755s + 0.7215s 17. Simona de Silvestro KV Dallara-Chevy 1m09.2779s + 0.7239s 18. Charlie Kimball Ganassi Dallara-Honda 1m09.3234s + 0.7694s 19. Marco Andretti Andretti Dallara-Chevy 1m09.3452s + 0.7912s 20. Sebastien Bourdais Dragon Dallara-Chevy 1m09.3480s + 0.7940s 21. Josef Newgarden Fisher Dallara-Honda 1m09.5084s + 0.9544s 22. Graham Rahal Ganassi Dallara-Honda 1m09.6315s + 1.0775s 23. JR Hildebrand Panther Dallara-Chevy 1m09.7176s + 1.1636s 24. Ed Carpenter Carpenter Dallara-Chevy 1m10.2947s + 1.7407s 25. Sebastian Saavedra Dragon Dallara-Chevy 1m10.4443s + 1.8903s 26. Ana Beatriz Coyne Dallara-Honda 1m11.2361s + 2.6821s