Josef Newgarden re-asserted himself as the points leader by taking his fourth win of the NTT IndyCar Season at the Iowa 300 at the Iowa Speedway in dominating fashion.

Heavy thunderstorms drenched the 7/8 mile oval just 30 minutes before the scheduled start of the race. Once the storms passed safety crews worked feverishly to dry the track and battled a rough patch of seeping water in Turn 4.

Their efforts were successful and the race started around 10:45 local time.

Will Power took the early lead from polesitter Simon Pagenaud while fourth-place starter Takuma Sato followed his tyre tracks to move up to second. Behind the leaders, Santino Ferrucci blasted from his 12th starting spot to move up to sixth by the end of the opening lap.

Power dominated what proved to be a short opening stint as Sage Karam spun into the path of Felix Rosenqvist on Lap 16 which brought out the first yellow flag.

Power comfortably picked up where he left off ahead of teammates Pagenaud and Newgarden and built up a 2.2-second lead. He soon faltered when he hit lapped traffic which allowed Newgarden to capitalize and take the lead on Lap 48 just before the yellow flag flew for a few sprinkles on the course.

The rain halted the action for 25 minutes and opened up the pit window when the track dried. Newgarden retained the lead ahead of Power and Pagenaud while Alexander Rossi and Takuma Sato followed behind.

Newgarden cleared his teammates on the restart while the action heated up behind them as Rossi and Santino Ferrucci engaged in a multi-lap duel for fifth place. The Dale Coyne Racing rookie eventually cleared the Andretti Autosport veteran as the pair closed on the fourth-place driver Sato.

Sato relinquished the position to the pair with Rossi eventually clearing Ferrucci who fell into the clutches of James Hinchcliffe. Sato dropped out of the top ten and became the first to make a green flag stop on 121.

He soon rocketed his way past the leaders with four fresh Firestone tyres to his advantage and made up a ton of time.

Newgarden pitted from the lead on Lap 142 with Power and Hinchcliffe following suit the very next lap.

Newgarden emerged as the leader with Sato’s tyre gamble putting him in second with Power riding close behind in third. Power eventually worked around the Japanese driver to take second as Newgarden extended his lead.

That lead allowed him to put championship rival Rossi down a lap on the 182nd circuit just after Sato kicked off the second green flag pit sequence on Lap 180.

Sato’s luck took a turn for the worse on Lap 187 when he drifted in front of Sage Karam which sent him spinning and brought out the yellow flag.

The yellow allowed the leaders to pit and allowed Rossi to take the waive around and get back on the leader lap.

The Lap 200 restart looked like a replay of the last with Newgarden pulling away from Power while Pagenaud moved around Spencer Pigot into third while Hinchcliffe passed Ed Carpenter for fourth.

Further back, an ailing Marco Andretti bunched up the pack which allowed Ferrucci to pass an astounding seven cars on the high line while Zach Veach moved up on the low line.

The Penske brigade gapped the field with Newgarden gapping Power in traffic up to five seconds by Lap 237. Pagenaud briefly mounted a charge but lost time fighting lapped cars as the race reached the 50 to go mark.

Pagenaud kicked off the final pit sequence on Lap 251. Power’s night then took a turn for the worse on the next lap when he locked and nearly clobbered the pit road attenuator. Newgarden meanwhile had a flawless stop and re-emerged as the leader as Power was given a stop and go penalty.

As he was serving his penalty, Ed Carpenter spun off Turn 2 which kept him from losing multiple laps under green.

The yellow was also a saving grace for Scott Dixon, who hadn’t made his final stop yet. He was followed on pit road by Rossi, Herta and Veach.

They lined up sixth, seventh and eighth while Newgarden led Pagenaud, Hinchcliffe, Pigot followed.

As he had done all night, Newgarden dropped the hammer on the restart while Dixon flew through the field on fresher tyres. The Kiwi entered the top five with 15 to go when he dispatched Pigot and soon inhaled Pagenaud with relative ease.

He passed Hinchcliffe for second just as effortlessly but found himself 2.3 seconds in arrears to Newgarden.

That proved to be as close as he got as Newgarden took his fourth win of the season.

Hinchcliffe rounded out the podium while Pagenaud finished fourth ahead of Spencer Pigot in fifth.

Rossi ended up in sixth ahead of Andretti Autosport teammate Zach Veach who claimed his best finish of his season in seventh.

Graham Rahal nursed an ailing Honda engine to eighth place in front of Sebastien Bourdain in ninth while Tony Kanaan completed the top ten.