Kiwi driver Scott Dixon has battled from the back of the grid to claim his fifth top-five finish of the season.
Starting in 13th after a disappointing qualifying run, the reigning series champion worked his way to the front of the pack to finish fourth in the Wisconsin race.
Chip Ganassi Racing teammate Alex Palou crossed the line first to move to the top of the IndyCar standings - 53 points clear of third-placed Dixon.
"I think if we started a little bit further up we should be okay," Dixon said post-race.
"I've got to work on that with the team and we'll get it going, but it was a good recovery for points."
Palou pounced on a late restart, when leader Josef Newgarden suffered engine trouble to win.
Polesitter Newgarden had looked poised to give Team Penske their first win of the season until his car, with two laps to run, suddenly lost power during a restart following a late caution, allowing Palou to shoot past him into the lead and gifting the young Spaniard and Chip Ganassi Racing the win.
Colton Herta took second for Andretti Autosport ahead of Penske's Will Power.
Former Haas Formula 1 teammates Kevin Magnussen and Romain Grosjean reunited on the starting grid, as Grosjean continued to shine in his maiden IndyCar season, finishing fifth for his second top-five result in the last four races.
Grosjean and Magnussen, who for four years were teammates at Haas before both were let go by the F1 outfit at the end of last season.
While Grosjean is running a full season with Dale Coyne Racing and already has a second-place finish, Magnussen made his IndyCar debut, filling in for Felix Rosenqvist at Arrow McLaren after the Swede was injured in a crash last Sunday in Detroit.
Magnussen - who made 119 Formula One starts for McLaren, Renault and Haas - qualified 21st of 25 cars but led for six laps through the midway part of the race, before retiring with mechanical issues with 15 laps to go.