Dario Franchitti fended off Will Power to take his second win of the IndyCar season at Lexington.
Helio Castroneves completed the podium, while Alex Tagliani led for much of the race thanks to a handy pit call, but ultimately had to settle for fourth for rookie squad Fazzt.
Polesitter Power had led at first for Penske, while third-place qualifier Takuma Sato (KV) briefly got ahead of Franchitti (Ganassi) for second before being re-passed a few laps later.
Having qualified back in 14th, Tagliani went out of sequence on pitstops, and his slightly early stop was then followed almost immediately by a full course yellow caused by KV's EJ Viso and Dreyer & Reinbold's Justin Wilson colliding while fighting over ninth place.
With everyone else pitting under the caution, Tagliani was able to cruise to the front of the queue behind the pace car, followed by Tony Kanaan - who had pitted much earlier having qualified down the order and gone off the road on the opening lap.
Just behind them, Franchitti got out ahead of Power, while Castroneves and team-mate Ryan Briscoe were able to continue in the lead pack despite three-way contact in the pits involving them and Andretti Autosport's Ryan Hunter-Reay, who had to pit again for repairs.
Kanaan had made his first stop too early to go the distance on just one more pit visit, but Tagliani was in great shape - confidently leading ahead of Franchitti and now on the same pit strategy as the other leaders.
But the Canadian did not manage to stay ahead through the final pit sequence, his slightly earlier stop seeing him fall behind Franchitti, Power and Castroneves, where he would remain.
That left Franchitti to resist everything Power could throw at him over the final laps to secure the win by a slender 0.5234 seconds.
Castroneves came home just ahead of Tagliani, Scott Dixon (Ganassi), Briscoe and late-charger Raphael Matos (De Ferran Dragon). HVM driver Simona de Silvestro had looked a likely top six contender for a while before fading to eighth - still a career-best - in the final stint.
Andretti's Marco Andretti took ninth, while the recovering Hunter-Reay edged Bertrand Baguette (Conquest) out of 10th in the closing laps.
Sato's superb weekend ended when he crashed at a restart while recovering from a slow pitstop.
Debutant JR Hildebrand was 16th for Dreyer & Reinbold in the end, escaping unscathed from a tangle that ended Sarah Fisher Racing driver Jay Howard's afternoon.
Pos Driver Team Time/Gap
1. Dario Franchitti Ganassi 1h54m32.2568s
2. Will Power Penske + 0.5234s
3. Helio Castroneves Penske + 4.0883s
4. Alex Tagliani Fazzt + 5.6423s
5. Scott Dixon Ganassi + 5.9150s
6. Ryan Briscoe Penske + 6.5100s
7. Raphael Matos De Ferran Dragon + 6.7518s
8. Simona de Silvestro HVM + 10.1451s
9. Marco Andretti Andretti + 10.9555s
10. Ryan Hunter-Reay Andretti + 13.2344s
11. Bertrand Baguette Conquest + 14.8260s
12. Mario Moraes KV + 16.0461s
13. Alex Lloyd Dale Coyne + 16.5570s
14. Dan Wheldon Panther + 19.3518s
15. Vitor Meira Foyt + 20.0782s
16. JR Hildebrand Dreyer & Reinbold + 20.2169s
17. Tony Kanaan Andretti + 25.4286s
18. Hideki Mutoh Newman/Haas + 26.5918s
19. Adam Carroll Andretti + 27.3302s
20. Graham Rahal Newman/Haas + 27.6341s
21. Danica Patrick Andretti + 28.2099s
22. Francesco Dracone Conquest + 3 laps
23. Milka Duno Dale Coyne + 4 laps
Jay Howard Sarah Fisher 38 laps
Takuma Sato KV 28 laps
EJ Viso KV 22 laps
Justin Wilson Dreyer & Reinbold 22 laps