Ryan Hunter-Reay earned his first win of the season following a farcical close to a chaotic and frequently interrupted race at New Hampshire.
The race swung on two of six restarts, with the first major incident coming when race leader Dario Franchitti - who had been utterly dominant in the opening third of the race - clashed with Takuma Sato, the Scot spearing into the pit wall and out of the race.
Ryan-Hunter Reay profited most by jumping into the lead, but the race swung again just eight laps from the end when stewards controversially decided to go green after a late shower had made a finish under the safety car seem likely.
The result was chaos - Danica Patrick spun from fifth, starting a melee which collected a gaggle of cars including title contender Will Power and ultimately led to a red flag, although with the surviving cars pulling into the pitlane it was not clear whether stewards intended to restart the race or call it to a premature halt.
After several minutes of delays and confusion, stewards ended the race and reset the results to before the final restart - handing Andretti Autosport's Hunter-Reay his first win of the season.
"A strange day, but sometimes racing is strange," Hunter-Reay said afterward. "We knew we had a good car this weekend, the guys have done a great job and it's a great result.
"It was the wrong move to restart, and I'm also sorry for Dario, but the team deserves this win. I wish it was a little bit different but we'll take it."
Newman Haas' Oriol Servia had jumped Hunter-Reay in the wet restart but to his chargrin was reset to second, with Ganassi's Scott Dixon completing the podium trio in third.
Servia's team-mate James Hinchcliffe completed a happy weekend for the team by finishing fourth ahead of Penske's Will Power, who was absolutely scathing of the officials following the decision to restart - particularly given the confusion immediately after, with Power at one point believing he would not be classified.
The Australian had been lapped by championship leader Dario Franchitti after just 56 laps of the race, but with the Scotsman crashing out of the race it became imperative he scored as many points as possible. His fifth-place moves him back to within 50 points of the overall lead.
Andretti's Danica Patrick, whose spin caused the late fracas, ended up sixth ahead of KV Racing's Takuma Sato, who apologised for his role in the earlier collision with Franchitti.
"No excuses, my fault," Sato confessed. "I was too close to Dario - he was coming on but I should have given him more space."
Penske's Ryan Briscoe, Ganassi's Charlie Kimball and AJ Foyt's Vitor Meira rounded out the top ten.
The tone of the race was set early on, as Andretti's Mike Conway got sideways and spun exiting Turn 2 on the very first lap, collecting Ganassi's Graham Rahal - who had been a contender for victory before a mistake in qualifying - and putting both out on the spot.
After a short safety car, the race restarted only for another incident exiting Turn 2 - this time Penske's Helio Castroneves spinning and stalling, although he was able to get going again and eventually finished 17th.
Tony Kanaan and Tomas Scheckter - deputising for the injured Justin Wilson - also caused a safety car interval when they clashed on lap 110, on the restart of which Sato and Franchitti came together.
For Franchitti, his first failure to finish since a race since Kansas in 2009 throws the championship wide open again.
"I didn't put a wheel wrong in the race, and I don't believe I did at the restart," he said. "When you have a car that fast its devastating..."
Results - 215 laps:
Pos Driver Team Time/Gap
1. Ryan Hunter-Reay Andretti 1h58m01.5843s
2. Oriol Servia Newman/Haas + 0.2361s
3. Scott Dixon Ganassi + 1.4839s
4. James Hinchcliffe Newman/Haas + 2.1750s
5. Will Power Penske + 2.8250s
6. Danica Patrick Andretti + 3.6173s
7. Takuma Sato KV + 4.1174s
8. Ryan Briscoe Penske + 1 lap
9. Charlie Kimball Ganassi + 2 laps
10. Vitor Meira Foyt + 3 laps
11. Ed Carpenter Sarah Fisher + 3 laps
12. EJ Viso KV + 3 laps
13. Alex Lloyd Dale Coyne + 4 laps
14. Ana Beatriz Dreyer & Reinbold + 5 laps
15. Sebastian Saavedra Conquest + 5 laps
16. Simona de Silvestro HVM + 6 laps
17. Helio Castroneves Penske + 13 laps
James Jakes Dale Coyne 176 laps
Alex Tagliani Sam Schmidt 137 laps
Dario Franchitti Ganassi 118 laps
JR Hildebrand Panther 118 laps
Tony Kanaan KV 109 laps
Tomas Scheckter Dreyer & Reinbold 109 laps
Marco Andretti Andretti 109 laps
Mike Conway Andretti 0 laps
Graham Rahal Ganassi 0 laps