Will Power went quickest in the IndyCar practice session around the streets of Baltimore.
The Australian established himself at the top early on with a 1m22.1384s effort, and aside from a brief intervention by Newman/Haas man James Hinchcliffe, remained the benchmark for the rest of the morning. The Penske improved his lap several times before finishing with a 1m.21.0176s.
Power's title rival Dario Franchitti was again second-fastest, falling just over 0.2s short of the Australian's time, while Franchitti's Ganassi stablemates Graham Rahal and Scott Dixon were third and fourth-fastest respectively.
The best of the non-Penske/Ganassi drivers was Sebastien Bourdais, who was fifth quickest for Dale Coyne Racing, with AJ Foyt Enterprises' Vitor Meira and Penske's Ryan Briscoe just behind him.
The morning was interrupted twice by full-course yellows, the first coming halfway in when Alex Tagliani became stranded on the track while attempting to reverse out of the run-off area at Turn 6.
That was followed by Marco Andretti overcorrecting after taking too much kerb at Turn 8 and being pitched into the barriers, putting himself out for the remainder of the session.
Pos Driver Team Time Gap 1. Will Power Penske 1m21.0176s 2. Dario Franchitti Ganassi 1m21.2393s + 0.2217s 3. Graham Rahal Ganassi 1m21.2661s + 0.2485s 4. Scott Dixon Ganassi 1m21.4238s + 0.4062s 5. Sebastien Bourdais Dale Coyne 1m21.5677s + 0.5501s 6. Vitor Meira Foyt 1m21.6481s + 0.6305s 7. Ryan Briscoe Penske 1m21.6501s + 0.6325s 8. James Hinchcliffe Newman/Haas 1m21.6729s + 0.6553s 9. Giorgio Pantano Dreyer & Reinbold 1m21.8485s + 0.8309s 10. Oriol Servia Newman/Haas 1m21.8735s + 0.8559s 11. Takuma Sato KV 1m21.8848s + 0.8672s 12. Ryan Hunter-Reay Andretti 1m21.9159s + 0.8983s 13. Ernesto Viso KV 1m22.0163s + 0.9987s 14. Charlie Kimball Ganassi 1m22.0295s + 1.0119s 15. Helio Castroneves Penske 1m22.1510s + 1.1334s 16. Tomas Scheckter Dreyer & Reinbold 1m22.2522s + 1.2346s 17. JR Hildebrand Panther 1m22.2936s + 1.2760s 18. Mike Conway Andretti 1m22.2992s + 1.2816s 19. Martin Plowman AFS/Sam Shmidt 1m22.4425s + 1.4249s 20. Alex Tagliani Sam Schmidt 1m22.5603s + 1.5427s 21. Simona de Silvestro HVM 1m22.5629s + 1.5453s 22. Tony Kanaan KV 1m22.6071s + 1.5895s 23. James Jakes Dayle Coyne 1m22.7735s + 1.7559s 24. Danica Patrick Andretti 1m22.8179s + 1.8003s 25. Marco Andretti Andretti 1m22.8789s + 1.8613s 26. Ana Beatriz Dreyer & Reinbold 1m23.4503s + 2.4327s 27. Sebastian Saavedra Conquest 1m24.0984s + 3.0808s 28. Ed Carpenter Sarah Fisher 1m24.6474s + 3.6298s