Team Penske's baffling lack of success at Iowa Speedway culminated with an awful performance Saturday night.
But points leader Juan Pablo Montoya remained in control of the championship race despite his first big bad break of the season.
Andretti Autosport driver Ryan Hunter-Reay claimed his third victory in Iowa in the last four years, leading the first U.S. podium sweep in nine years and giving Andretti its sixth consecutive win on the 0.894-mile oval.
Penske star Montoya, the reigning Indy 500 champion and the points leader since winning the opener, crashed on the ninth lap.
Though the wreck threatened to put Montoya's cushy lead in jeopardy, his lead dropped from 54 points to just 42 ahead of Graham Rahal.
Will Power's 10th-place finish was the best of yet another shaky race in Iowa for Penske. Helio Castroneves was 11th despite starting from the pole and Simon Pagenaud finished 14th.
Montoya finished last for the first time in 2015.
But he's still first in the race that matters most heading into the Mid-Ohio event Aug. 2.
"Something broke. As soon as I let it up, something gave out," Montoya said. "It sucks when it's completely out of our hands, when something fails."
Josef Newgarden was second and Chip Ganassi Racing rookie Sage Karam was a career-best third, putting Americans in the top three spots for the first time since the 2006 Indianapolis 500.
"It's very important to note that it's an international series ... so when Americans do (well) and beat the rest of the world it's great," said Andretti owner Michael Andretti, who as a driver was part of the podium sweep at Indy in '06. "To do it here in the heartland...it's pretty cool."
Ganassi's Scott Dixon was second behind Montoya heading into the weekend and was poised to make up major ground. But he finished 18th after a mechanical issue and fell to third, gaining just six points on his Colombian counterpart.
Hunter-Reay, the 2012 series champion, had been among the more high-profile drivers to struggle with Honda's engine and aero kit this season.
But Hunter-Reay always seems to run his best in Iowa.
Hunter-Reay, who used fresh tires to get past half the field in the final 10 laps to win in 2014, raced to his 15th career win and gave beleaguered Honda just its fourth victory in 13 starts.
"(My car) was on rails until the end. I was driving the snot out of it. It was loose, and I just kept my foot to the floor," Hunter-Reay said. "It was a lot of work in the cockpit. This was one we really had to work for."
Newgarden wound up second at Iowa for the second year in a row, as he simply ran out of time in his late pursuit of Hunter-Reay.
"I think I probably needed another 20 laps or so and some lapped traffic. I think I could have done something with (Hunter-Reay). But it was really tough," Newgarden said. "I think we were a winning car, so to finish second was bittersweet."
It wasn't a shock to see the 20-year-old Karam have his breakthrough at Iowa after he won races here in four separate ladder series.
Karam did so with some maneuvering that left some of his competitors steamed. Ed Carpenter even confronted the rookie after a close encounter between the two, though the altercation didn't become physical.
"He's just angry at my driving," Karam said. "He says I squeezed him a few times, but it's the same way he drove me."
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