Australia's Will Power won Sunday's storm-shortened and crash-marred Pocono 500, stretching his string of IndyCar seasons with a victory to 13 while American Josef Newgarden boosted his season points lead.
Racing was stopped for lightning after 128 of 200 scheduled laps over the unique 2.5-mile (4km) tri-oval course at Long Pond, Pennsylvania.
A few minutes later, leader Power was declared a winner with New Zealand's Scott Dixon second, France's Simon Pagenaud third, US rookie Santino Ferrucci fourth and Newgarden fifth.
"Over the moon," Power said. "I had a few issues during the race but I just kept coming back. When it was time to go I went. I was so determined.
"It'll be my 13th year in a row winning a race. I had been thinking about that."
Power won at Pocono in 2016 and 2017 and was second last year, but it was only his second victory since taking last year's Indianapolis 500. He will defend his only other title next week at Gateway in Madison, Illinois.
The race was marred by a stunning first-lap crash that caused no severe injuries but involved five of the 22 drivers, including defending race champion Alexander Rossi, whose season title hopes suffered a blow despite a front-row start.
Newgarden improved his gap over Rossi from 16 to 35 points with three races remaining in the season, although Dixon, the defending IndyCar season champion, and Pagenaud, this year's Indianapolis 500 winner, tightened their gap behind Rossi.
It was Dixon's fourth consecutive top-two finish.
A qualifying rainout left season points to decide starting spots with Newgarden on the pole alongside 2016 Indy 500 winner Rossi and Pagenaud and Dixon in row two.
But just outside the second turn of lap one, Japan's Takuma Sato moved down from the outside, his left rear tire hitting the front right tire of Rossi's car, sending Sato careening into Ryan Hunter-Reay, the crash also collecting Swedish rookie Felix Rosenqvist and James Hinchcliffe.
Rosenqvist, who was evaluated at a nearby hospital and released, skidded along the outer retaining wall and fence in a wreck eerily like one last year that left Canadian racer Robert Wickens unable to walk.
"I can't even begin to understand how after last year Takuma thinks any sort of driving like that is acceptable," Rossi said. "Turning across two cars like that at that speed is disgraceful and upsetting."
"This is ridiculous," Hunter-Reay said. "I thought we learned our lesson here... it all hand-grenaded."
"After last year, I don't think anybody had to say anything," said Hinchcliffe. "It's such a waste."
Sato explained: "I thought it was all clear. Everybody got close and unfortunately we made contact. I'm not really overly aggressive overtaking or anything."
Rossi strategist Rob Edwards saw it differently, saying, "Someone made something pretty silly happen going into turn two."