The rain-delayed race suffered a brief interruption due to further rain but it was a largely incident-free event.
Scott Dixon led the field away at the start but it was Dario Franchitti who quickly moved into the lead. His Andretti-Green team mate Tony Kanaan then nicked second of Dixon who fell to third ahead of Dan Wheldon.
Franchitti was able to make rapid progress through traffic. But team mate Franchitti took one risk too many and on lap 36 lost the car lapping Sarah Fisher and hit the wall.
That brought out the yellow flags for the first time and kicked off the first set of pit stops. The top three stayed the same, but Helio Castroneves passed Wheldon only to lose the place once again on the next lap. He dropped back slightly leaving Franchitti and the Ganassi team mates at the front, covered by less than a second.
Behind Castroneves were Danica Patrick, Sam Hornish Jnr, Marco Andretti and Scott Sharp.
By lap 76 the leaders were lapping Fisher again and this time it was Wheldon who was delayed and shook his hand at the Dreyer & Reinbold racer. He fell to two seconds behind leader Franchitti but quickly began cutting the gap.
Wheldon then used the traffic to his benefit to get past team mate Dixon, moving into third on the 83rd lap. Franchitti responded to the threat by setting his fast lap so far on the 86th circuit.
The leaders hit traffic once again and this time things got really hectic. Somehow Dixon emerged ahead with Wheldon second and Franchitti third.
The second round of pit stops began and Dixon kept his lead but Wheldon fell back after he tried to leave his pit too soon. No sooner was he back on track than light rain started to fall, prompting another caution period.
It was almost 20 laps before the race Lap 109 saw the race resume with Dixon leading Franchitti, with Wheldon passing Andretti for third on lap 122.
But the Briton was unable to catch the leaders and fell to six seconds by Dixon by lap 144.
Lap 151 saw Franchitti pit followed by Dixon and Patrick three laps later. The next tour saw Wheldon, Scott Sharp, Hornish and Andretti all pit. Once again it was Wheldon who suffered a slow stop, falling to seventh behind Patrick, Sharp, Andretti and Hornish.
Up front Dixon made very rapid progress through the traffic, pulling out a 5.8s lead over Franchitti by lap 174. Patrick now ran third but over ten seconds – nearly half a lap – behind Dixon.
The positions looked set but on lap 188 Jeff Simmons spun across the infield grass and was narrowly missed by Kosuke Matsuura. The Japanese driver hit the wall but fortunately avoided a terrible accident that might have looked like Alessandro Zanardi’s terrible crash in 2001. Simmons was able to continue.
The field closed up for a final five-lap blast to the flag. But Franchitti couldn’t get near to Dixon and the New Zealander won his second race in a row. Franchitti limited the damaged to his championship lead with second, and Patrick had another strong finish with third.
Hornish, Andretti and Castroneves were fourth, fifth and sixth after they all passed Sharp at the restart. Wheldon finished eighth after his problems, one place ahead of compatriot Darren Manning with Vitor Meira completing the top ten.
The string of IRL races continues – the series is at Mid Ohio next weekend.