Andretti Autosport's Ryan Hunter-Reay was quickest in the first IndyCar practice session of the season in St Petersburg.
The American jumped to the top with his last lap, a 1m04.1437s that placed him 0.0388 seconds ahead of 2010 championship runner-up Will Power's Penske entry.
Mike Conway made it two Andretti cars in the top three with his late leap to third, as the Briton builds towards his first race back following his horrific crash in last year's Indianapolis 500.
Long-time pacesetter Scott Dixon was fourth in the end, with his Ganassi team-mate and reigning champion Dario Franchitti sixth between Penske's Ryan Briscoe and Helio Castroneves.
EJ Viso was the quickest KV driver in eighth but also had the morning's only incident, when he crashed on the exit of Turn 3 in the final moments.
KV's last-minute recruit Tony Kanaan quickly settled into his new surroundings with 12th place, just behind team-mate Takuma Sato.
Andretti's Marco Andretti and Dreyer & Reinbold's Justin Wilson - who led the timesheets for a while - filled the final top-10 positions. Sebastien Bourdais was back in 20th in the Dale Coyne car.
Pos Driver Team Time Gap 1. Ryan Hunter-Reay Andretti 1m04.1437s 2. Will Power Penske 1m04.1825s + 0.0388s 3. Mike Conway Andretti 1m04.2228s + 0.0791s 4. Scott Dixon Ganassi 1m04.3184s + 0.1747s 5. Ryan Briscoe Penske 1m04.3525s + 0.2088s 6. Dario Franchitti Ganassi 1m04.3643s + 0.2206s 7. Helio Castroneves Penske 1m04.4215s + 0.2778s 8. EJ Viso KV 1m04.5397s + 0.3960s 9. Marco Andretti Andretti 1m04.6672s + 0.5235s 10. Justin Wilson Dreyer & Reinbold 1m04.7114s + 0.5677s 11. Takuma Sato KV 1m04.7668s + 0.6231s 12. Tony Kanaan KV 1m04.8591s + 0.7154s 13. Oriol Servia Newman/Haas 1m04.9504s + 0.8067s 14. Alex Tagliani Schmidt 1m04.9827s + 0.8390s 15. Graham Rahal Ganassi 1m04.9983s + 0.8546s 16. Raphael Matos AFS 1m05.1760s + 1.0323s 17. Sebastian Saavedra Conquest 1m05.2207s + 1.0770s 18. Vitor Meira Foyt 1m05.2705s + 1.1268s 19. Danica Patrick Andretti 1m05.4240s + 1.2803s 20. Sebastien Bourdais Dale Coyne 1m05.5265s + 1.3828s 21. James Jakes Dale Coyne 1m05.9182s + 1.7745s 22. Charlie Kimball Ganassi 1m05.9305s + 1.7868s 23. JR Hildebrand Panther 1m05.9704s + 1.8267s 24. Ana Beatriz Dreyer & Reinbold 1m07.2488s + 3.1051s 25. Simona de Silvestro HVM 1m07.5267s + 3.3830s