Scott Dixon finished second in yesterday's Iowa 300 but lost ground to IndyCar leader Josef Newgarden after the American clinched his fourth victory of the season.
Newgarden led for 245 of the 300 laps and won the weather-delayed race yesterday at Iowa Speedway and now has 487 points.
With five of 17 races remaining, Kiwi driver Dixon is fourth overall, 98 points behind Newgarden.
Newgarden's run resembled his dominant win on Iowa's short oval in 2016, when he led a series-record 282 laps in Newton.
"We've got to keep going. It's a long way," Newgarden said. "It helps, but we've got to keep it up. There's a lot of guys still in it."