NEWTON, Iowa — Last season, Ryan Hunter-Reay strung together back-to-back wins at Milwaukee and Iowa during a stretch that was crucial in clinching his first IndyCar Series title.

If Hunter-Reay can repeat the Milwaukee-Iowa sweep again this weekend, the defending champion could find himself back in first place in the points chase.

Hunter-Reay heads into Sunday's race at Iowa Speedway in fantastic form. The win at the Milwaukee Mile last week was Hunter-Reay's fourth podium finish in five races, and he's now just 16 points behind series leader Helio Castroneves.

"Knowing that the potential is there is probably the biggest pressure that you can have. That you know you can get it done if you and the team just operate to your full potential," Hunter-Reay said. "We'll see. We know it's going to be challenging because there's other teams that have progressed this year and have improved, so we'll go out there, look at what we did last year and try and make it better this year."

In a series that's proven to be unpredictable in 2013, Hunter-Reay has been about as consistent as anyone outside of Castroneves.

He was knocked out twice in his first three events; done in by a bad throttle in the opener in St. Petersburg and by a crash at Long Beach. He then finished just 11th in Sao Paulo after winning the pole.

But he sandwiched a win at Birmingham in between the first two incidents to stay within close range of the top of the leaderboard.

In the last five races, the No. 1 Andretti Autosport car has been by far the best one on the circuit.

Hunter-Reay was third at the Indianapolis 500 and second in the first of two races at Belle Isle. He was second at Texas and first in Milwaukee — both ovals like the .875-mile one he'll run this weekend — and he's led laps four times in the last five events.

"Everything," Hunter-Reay said when asked about what's been going right of late. "Having a steady ride, a solid home, one of the best teams in racing, especially in IndyCar, and just having that support system."

Despite all of his recent success, Hunter-Reay has yet to catch up to Castroneves.

That's a tribute to how well the No. 3 Team Penske car has run all season.

Castroneves is still chasing that elusive first IndyCar title despite over a decade of consistent success. But Castroneves has four podium finishes, including a win at Texas, and he's been in first place for all of June.

"To be honest, it's been a credit to the team," Castroneves said. "Week in and week out, it's the small details that we've focused on."

Still, Iowa has been a mystery that neither he nor anyone else at Team Penske has been able to solve.

Even though the Penske cars have routinely come into Iowa Speedway with perhaps the strongest roster in the field and have twice won poles, they've never won a race here in six tries.

Castroneves has been particularly vexed by Iowa. He's started on the front row four times, but the best he's been able to do is a runner-up finish in 2010.

"We've led so many laps here," said a chuckling Castroneves. "You can't give up. It wasn't meant to be, and hopefully it will be this year."

Part of the problem for Penske has been Andretti Autosport.

Andretti drivers are four for six at Iowa; including three straight winners in Tony Kanaan, Marco Andretti and Hunter-Reay a year ago.

If Hunter-Reay can make it four straight and two in a row for the No. 1 car, he might just leave Iowa with the points lead. But Castroneves isn't ready to concede anything yet to the surging Hunter-Reay.

"They're very competitive. They're very strong. But I'm not focusing on what they have. I'm focused on what we can do to be competitive, you know? I trust in my boys. I trust in myself," Castroneves said.