An unexpected mechanical issue for Newgarden made the job easier.
Palou sailed beyond Newgarden on a restart with two laps remaining to win Sunday's race and proceed back atop the IndyCar points standings. It marked the third consecutive race a Team Penske car dominated but did not win because late warnings shifted what seemed to be certain successes.
"We began struggling in comparison with Josef," Palou explained. "He was super fast. He was flying. But by the end I was able to be there with himso that I believe we had the quicker car in the end. I knew that we had a little better flat-rate rate ."
Palou won by 1.9106 seconds over Colton Herta of all Andretti Autosport.
The success gives Palou a 28-point guide over Pato O'Ward, who finished ninth in Sunday's race. Palou entered the weekend trailing O'Ward by one stage.
"There's a great deal of motion on points," Palou said. "It's likely to keep it going until the last race, I presume."
Newgarden started in the pole and headed 32 of those 55 laps until Ed Jones' twist brought out the yellow with four to proceed. Newgarden got a fantastic jump on the restart but Palou dipped left and sped him around to get the lead.
Newgarden had a mechanical problem and plummeted from the lead to a 21st-place finish.
"I couldn't get it to shift into sixth gear," Newgarden said. "And I made it stuck in fifth turn one and finally got it to go down, but just could not get it to upshift then. So I got it down to first essentially. So just trying to stay out of the way then because I couldn't get it to upshift after that."
Newgarden has directed 99 of 125 laps the last two IndyCar races however does not have a win to show for it. He had been denied a victory a week ago in Detroit if O'Ward ran him down following another late restart.
The driver who led the most laps hasn't won in IndyCar the last six races, and Team Penske is still searching for its first victory of the year through nine races. It is the strangest into a season Penske has gone without a success since moving winless in 1999.
"I can't believe the luck having as a team right now.
It was the second consecutive weekend a mechanical difficulty doomed Team Penske. Power dropped the first race of last weekend doubleheader in Detroit since his car would not start after a late red flag.
"You just don't understand what it is all about our team right now," Power said. "We nearly have a win in the bag and some thing just ridiculous occurs. I don't know what it was, but things you could not prep for, something that you couldn't avoid. My thing was just a change, only a weird glitch in the machine, in Detroit.
"I don't know what his was this moment, but incredible. Perhaps it wouldn't have happened if there was not a restart. You don't know."
Palou became the first Chip Ganassi racing driver other than Scott Dixon to win multiple races in a season since Dario Franchitti at 2011.
Dixon and Felix Rosenqvist won the two races at a Road America doubleheader last year.
Palou, Dixon and Marcus Ericsson place three of Ganassi's four automobiles Within the top-six at Road America. Seven-time NASCAR champion Jimmie Johnson was 22nd at Ganassi's fourth car.
Cody Shane Ware, that typically competes in NASCAR, finished 19th in his IndyCar debut. Kevin Magnussen, Grosjean's teammate in Formula One before both were released at the end of last season, was 24th in his IndyCar debut. The Danish driver has been that the replacement for Rosenqvist, that drives for Arrow McLaren SP and has been injured last week in an accident at Detroit.
"I will leave here with a huge smile on my face though we didn't finish the race because of a mechanical issue," Magnussen said. "I have had a really fun experience and wish to say thank you to everybody involved."
Oliver Askew was 12th as the injury replacement for Rinus VeeKay, who broke his collarbone Monday when dropped of his bike during a training trip. VeeKay was fifth in points before missing Sunday's race and is currently sixth in the standings.