Instead, Dixon got taken out in one last crash to end a wild race at the repaved and reconfigured 1 1/2-mile track and Power won under caution. Only eight of the 22-car field actually crossed the finish line Saturday night.
Power, who led 180 of the 248 laps, was the leader when Dixon got wrecked by Takuma Sato, and finished ahead of Tony Kanaan, who other drivers and at least one owner blamed for a big crash earlier that led to a nearly 31-minute red flag.
"Apparently I got blamed for all of them," Kanaan said. "Got a penalty, paid a penalty, and we finished second."
The final caution came when Sato, driving the same car in which he won the Indianapolis 500 in two weeks ago and pushing for another win, got his left side slightly into the grass on the front stretch with five laps to go. That sent him spinning and also took out Dixon.
"It was a pretty intense battle there at the end with Scott," Power said. "I was kind of working out in my head how I was going to get him over the line because he was kind of able to side draft me and be ahead on some laps, so it was really going to be an interesting finish."
Power's 31st career victory, and second this season, was indeed interesting.
Simon Pagenaud was third, ahead of defending race champion Graham Rahal, who was coming of winning both races at Detroit last week to become the first IndyCar driver this season with multiple victories. Gabby Chaves finished fifth and Marco Andretti in sixth was the only other driver to finish all 248 laps at the 1 1/2-mile track.
"It was pretty nerve-wracking out there," Pagenaud said.
With a full moon looming over the track, the red flag came out after an accident involving eight other cars that was blamed on Kanaan, who recovered from the ensuing penalty for his runner-up finish.
James Hinchcliffe got loose on lap 154 after making contact with Kanaan, who appeared to move up the track into him. That put Hinchcliffe in the middle of three-wide, and he made contact with his Schmidt Peterson Motorsports teammate Mikhail Aleshin.
While calling Kanaan someone he trusts on the track, Hinchcliffe said Kanaan drove from inside along the white line and up into him, and pushed him into Aleshin.
"He wasn't driving smart, or respectfully," Hinchcliffe said.
That led to a spark-spraying chain reaction that took out both Dale Coyne Racing drivers, Tristan Vautier and Ed Jones, and sent driver-owner Ed Carpenter and his teammate JR Hildebrand to the garage. Carlos Munoz and Ryan-Hunter Reay were knocked out of the race.
Carpenter, who took his repaired car back on track 12 laps down, also blamed Kanaan. Car owner Dale Coyne went up to Kanaan's car while it was lined up on pit road during the red flag, then leaned into the cockpit and said something.
After the race resumed, IndyCar penalized Kanaan for avoidable contact, holding him in his pit for 20 second during green-flag conditions.
All drivers involved in the crash were evaluated and released from the infield care center.
IndyCar enforced two mandatory stops under caution after that for tire changes after 30 green-flag laps on each set. There was blistering of some tires on the fresh pavement of the track, including Helio Castroneves wrecking out earlier in the night.
The series said in a statement after the race that, after consulting with Firestone, those extra stops were added "out of an abundance of caution as race conditions presented different conditions than seen in earlier tests."
Rossi, the 2016 Indy 500 winner as a rookie, spun and made hard contact with the wall after getting pinched between Dixon and Kanaan, then bouncing of both of the Chip Ganassi Racing cars while coming off the backstretch on lap 37.
During stops on the ensuing caution, Sato got pinned into the wall during a pit road collision that damaged the front wing of his car. Hinchcliffe got loose coming out of his pit, then swerved into Castroneves at the same time Sato was pulling out of the first stall.
Hinchcliffe was penalized for avoidable contact.
Before the green flag came out again, polesitter Charlie Kimball's car was pushed to the garage because of an oil leak and done.
Castroneves, a three-time Indianapolis 500 winner who was the runner-up to Sato this year, was running third behind Team Penske teammates Power and Pagenaud when his front right tire gave and his car veered into the wall coming out of the second turn on lap 91. Castroneves went hard into the wall and eventually came to rest on the inside of the third turn.
After three races in two weekends since the month of May at Indianapolis, the IndyCar Series takes a week off before its next race June 25 at Road America, the four-mile, 14-turn road circuit in Wisconsin.