Scott Dixon has taken his first Indianapolis 500 victory, holding off Vitor Meira, Marco Andretti and Helio Castroneves.
The 2003 IndyCar champion was one of the main contenders throughout the race, and was able to edge away from the chasing pack in the final sprint to the flag after the last pitstops.
"What a day," said Dixon in Victory Lane. "I just can't believe it - I just thought something was going to go wrong."
The Ganassi driver, who also took pole position a fortnight ago, had to maintain his composure through a race that featured eight yellow flag periods for a total of 69 laps. He ultimately led a commanding 115 out of 200 laps, yet was never able to absolutely dominate.
"We seemed to have a good car and we just had to hold on to it at all the restarts," he added. "With so many yellows, you were always a sitting duck and it was really hard to get into a rhythm."
Panther Racing's Meira, who briefly led prior to the final stops, tried his hardest to chase down the Ganassi driver while fending off the charging Andretti, but was unable to get close enough.
"I certainly did my best today, and so did the crew," Meira said. "We really, really prepared this car, and everything was according to plan, but things didn't really happen our way."
Ganassi dominated the first half of the race, with Dixon and teammate Dan Wheldon holding a commanding one-two, but after half-distance they faced strong challenges from Tony Kanaan, Andretti, Meira, Tomas Scheckter and Helio Castroneves.
Wheldon tumbled out of contention for the victory as his car's handling faded, and he eventually fell back to a distant 12th place.
"My issue was with the right rear," Wheldon said. "It was OK in the first few stints, but it seemed to get worse and worse as the race went on. It was very difficult."
Kanaan charged past both Ganassi cars to lead at the halfway point, only to crash out while battling with teammate Andretti, who was trying to pass Kanaan on the inside just as Dixon edged ahead of the outside. Trying to avoid Andretti, Kanaan hit the wall and spun back into the path of Sarah Fisher, taking both cars out and leaving the Brazilian furious with his young teammate.
When told that Andretti had said he was sorry via radio, Kanaan replied, "He better be. It was a very stupid move, especially on a teammate."
Andretti said he didn't intend to force Kanaan out of the groove: "In hindsight, it's easy to point out mistakes."
After this crash, Dixon, Andretti and Scheckter made a break from the pack, until the latter was eliminated by a driveshaft failure at his final stop.
"It's a pity," Scheckter said. "These things sometimes happen. It is the worst time."
A very swift service by the Panther crew brought Meira into contention at the same time, and he led for a while after diving between the dicing Dixon and Ed Carpenter, who was running up front while out of sequence on pitstops.
Dixon was able to get back around Meira, leaving the Brazilian to fend off Andretti to the flag as the latter tried to regain ground after a relatively slow final stop.
Penske had a low-key start to the race, with Ryan Briscoe losing a lap after pitting with a vibration, and Castroneves needing a new front wing after striking debris from Marty Roth's crashed car.
But both drivers edged into contention in the final laps, as Castroneves held third for a while before losing the place to Andretti. He then resisted pressure from Carpenter and Ryan Hunter-Reay to secure fourth.
Briscoe got back into the top ten before a controversial clash with Danica Patrick in the pit exit ended both their races. The enraged Patrick strode towards the Penske pit to remonstrate with Briscoe, but was turned away by series security officials.
"It's probably best that I didn't get there," she said.
Hunter-Reay beat AGR's Hideki Mutoh to the race's rookie of the year honours, but had hoped for better than sixth.
"I'm disappointed that we didn't get more results," Hunter-Reay said. "I really think this was a seventh-place car and we finished sixth with it."
Mutoh finished seventh, followed by Dreyer & Reinbold's Buddy Rice, who led eight laps early in the race after staying out when most of the field pitted.
Darren Manning (Foyt) took ninth despite a pitlane clash with Alex Lloyd removing his front wing at one stage, while Townsend Bell rounded out the top 10 to complete a fine day for Dreyer & Reinbold.
Oriol Servia was the best of the ex-Champ Car drivers in 11th, two places ahead of his KV Racing teammate Will Power.
Newman/Haas/Lanigan duo Graham Rahal and Justin Wilson both crashed out, while Bruno Junqueira headed his fellow transition drivers in the early laps and even led when those ahead pitted, only to be summoned in because one of his mirrors had become detached and caused the first yellow.
Other drivers who finished despite eventful races included Milka Duno - who looked set to finish on the lead lap until a late brush with Buddy Lazier - and AJ Foyt IV, who escaped a dramatic fire at his first pitstop.
Lloyd, Jaime Camera and Jeff Simmons were the other drivers to crash out, with British rookie Lloyd pirouetting down the pitlane after a crash at the final corner, and Simmons hitting the wall while trying to warm his tyres under yellow.
Pos Driver Team Time 1. Scott Dixon Ganassi 200 laps 2. Vitor Meira Panther + 1.7498 3. Marco Andretti Andretti Green + 2.3127 4. Helio Castroneves Penske + 6.2619 5. Ed Carpenter Vision + 6.5505 6. Ryan Hunter-Reay Rahal Letterman + 6.9894 7. Hideki Mutoh Andretti Green + 7.8768 8. Buddy Rice Dreyer & Reinbold + 8.8798 9. Darren Manning Foyt + 9.2019 10. Townsend Bell Dreyer & Reinbold + 9.4567 11. Oriol Servia KV + 22.4966 12. Dan Wheldon Ganassi + 30.7090 13. Will Power KV + 31.6666 14. Davey Hamilton Vision + 32.0084 15. Enrique Bernoldi Conquest + 32.1075 16. John Andretti Roth + 1 lap 17. Buddy Lazier Hemelgarn + 5 laps 18. Mario Moraes Dale Coyne + 6 laps 19. Milka Duno Dreyer & Reinbold + 15 laps 20. Bruno Junqueira Dale Coyne + 16 laps 21. AJ Foyt IV Vision + 20 laps 22. Danica Patrick Andretti Green + 29 laps 23. Ryan Briscoe Penske + 29 laps 24. Tomas Scheckter Luczo Dragon + 44 laps 25. Alex Lloyd Rahal Letterman/Ganassi + 49 laps 26. EJ Viso HVM + 61 laps 27. Justin Wilson Newman/Haas/Lanigan + 68 laps 28. Jeff Simmons Foyt + 88 laps 29. Tony Kanaan Andretti Green + 95 laps 30. Sarah Fisher Sarah Fisher + 97 laps 31. Jaime Camara Conquest +121 laps 32. Marty Roth Roth +141 laps 33. Graham Rahal Newman/Haas/Lanigan +164 laps