Helio Castroneves beat Scott Dixon to victory at Chicagoland by a few fractions of a second, but it was Dixon who claimed the IRL IndyCar Series title.
Although the timing screens suggested that Ganassi driver Dixon had held off his Penske rival by 0.0010 seconds, close scrutiny of the video footage revealed that Castroneves had nosed ahead across the line and snatched the win despite starting last - although second place was still enough for Dixon to clinch his second championship.
Castroneves' Penske teammate Ryan Briscoe completed the podium in a very close third.
Tony Kanaan finished fourth for Andretti Green Racing, as KV Racing's Will Power charged to fifth in the closing stages.
Ganassi's Dan Wheldon faded to sixth after challenging for the lead for much of the race, while Darren Manning (AJ Foyt Racing), Marco Andretti (AGR), Ryan Hunter-Reay (Rahal Letterman) and Danica Patrick (AGR) filled the rest of the top ten places.
Briscoe led the opening laps under heavy pressure from Kanaan, while Dixon lurked in third place and Castroneves picked his way through the midfield after his qualifying penalty, soon reaching the edge of the top ten.
He then gained several more places in the first pitstops, which came under yellow after Ed Carpenter - who had charged to fourth early on - crashed following an apparent mechanical failure on his Vision Racing car.
Kanaan jumped into the lead at the stops, while Castroneves continued to make progress when racing resumed, passing title rival Dixon for third on lap 65, and then leaping to first place in the next pitstops, which again took place during a caution following a single-car crash for Vitor Meira in his final start with Panther Racing.
Dixon then had a major scare in the next stint as his car lost pace and fell as low as 10th, while Castroneves led from Briscoe, Wheldon and Kanaan. But as the race approached its final stages, Ganassi charged back into contention, with Dixon rejoining the front group and Wheldon repeatedly swapping the lead with Castroneves.
When the final stops came under yellow with 18 laps remaining, it was Dixon who emerged from the pits first and proceeded to resist enormous pressure from Castroneves until the final corner, when the Penske Dallara-Honda just edged ahead on the outside to claim a consolation win.
The result was not only the closest finish in series history, with Castroneves winning by just 0.001 seconds, but also saw Castroneves set a new record from coming back from 28th on the grid to take victory.
The race saw spectacular pack racing in the top ten all afternoon and just four seconds covering the top 12 at the chequered flag, although several drivers were left ruing their misfortune after losing out on or throwing away potentially great results.
Both EJ Viso (HVM) and Mario Moraes (Dale Coyne Racing) crashed out after charging drives that saw them come from the back of the grid to run in the top five before a puncture for Viso and a late brush with the wall for Moraes.
Other drivers whose promising top six runs ended in disappointment included Graham Rahal, who was penalised for taking Buddy Rice out in a pit lane collision and later hit the wall, Tomas Scheckter, who suffered floor damage on debris, AJ Foyt IV, who spun on the final lap, and Patrick, who lost ground by pitting under green just before a caution in the closing stages.
Pos Driver Team Time 1. Helio Castroneves Penske 200 laps 2. Scott Dixon Ganassi + 0.0033 3. Ryan Briscoe Penske + 0.0788 4. Tony Kanaan Andretti Green + 0.6095 5. Will Power KV + 1.3580 6. Dan Wheldon Ganassi + 1.8729 7. Darren Manning Foyt + 2.3224 8. Marco Andretti Andretti Green + 2.4627 9. Ryan Hunter-Reay Rahal Letterman + 2.7993 10. Danica Patrick Andretti Green + 2.9276 11. Justin Wilson Newman/Haas/Lanigan + 3.0218 12. Alex Tagliani Conquest + 4.2072 13. AJ Foyt IV Vision + 1 lap 14. Milka Duno Dreyer & Reinbold + 1 lap 15. Franck Perera Foyt + 2 laps 16. Marty Roth Roth + 3 laps 17. Oriol Servia KV + 4 laps 18. Jaime Camara Conquest + 13 laps 19. Graham Rahal Newman/Haas/Lanigan + 14 laps 20. Bruno Junqueira Dale Coyne + 16 laps 21. Mario Moraes Dale Coyne + 19 laps 22. Hideki Mutoh Andretti Green + 23 laps 23. EJ Viso HVM + 64 laps 24. Sarah Fisher Sarah Fisher + 84 laps 25. Buddy Rice Dreyer & Reinbold + 90 laps 26. Tomas Scheckter Luczo Dragon +113 laps 27. Vitor Meira Panther +126 laps 28. Ed Carpenter Vision +164 laps