After a season of adjustment in joining Team Penske, Simon Pagenaud emerged as a Verizon IndyCar Series champion with a dominant 2016.

That Josef Newgarden, in his first year driving for Roger Penske, has positioned himself to claim the title at Sunday’s GoPro Grand Prix of Sonoma is a testament to his growth as a driver.

Specifically, Newgarden cites his ability to assimilate to everything this season. It starts with a new team, albeit the most successful in Indy car history. Beyond that, there’s the benefit of working and sharing information with such successful teammates in Pagenaud, 2014 series champion Will Power and three-time Indianapolis 500 winner Helio Castroneves. 

And although Newgarden has won three of the past five races to take a three-point series lead into this double-points season finale, he’s reminded by a mistake in his last start that there’s always room to grow.

“You're always learning, as evidenced by Watkins Glen,” he said of a pit exit mistake that dropped him to finish 18th and kept as many as six other drivers mathematically capable of winning the title. “Hopefully that turns into a learning experience for me and not just an error.

“I think you're always trying to evolve on what did you do well, what did you not do well, what would you do differently, and hopefully I'm not leaving Sonoma saying, ‘Well, I wish I could have done this differently’ and more just I'm happy with how we executed and how we handled things.”

The 26-year-old Tennessean caught Penske’s eye with three wins in the previous two years while driving for Ed Carpenter Racing and CFH Racing. With Team Penske president Tim Cindric as his strategist, Newgarden won the first of four races this season in his third start, at the Honda Indy Grand Prix of Alabama in April.

Before Watkins Glen, he was dominating much like Pagenaud did with five wins a year ago. Newgarden won the Honda Indy Toronto and Honda Indy 200 at Mid-Ohio in back-to-back starts in July, finished second in the ABC Supply 500 at Pocono Raceway and prevailed in the Bommarito Automotive Group 500 on Aug. 26.

“I think for me personally, just being more adaptive is what's been my biggest growth point this year, being able to adapt to a different environment that works differently than I've experienced in the past, being able to adapt to different setups that aren't necessarily in my comfort window,” Newgarden said. “(It’s) not something that I've had my personal touch on right from the beginning, which is what I've been used to in the past with the teams I've worked with the in the past.

“Just being able to adapt throughout the year has been probably my biggest strength and growth, and I'm hoping that we continue to grow in that department and are able to use that going into next year after Sonoma this season.”

Those trying to chase him down include four-time series champion Scott Dixon of Chip Ganassi Racing, who is just three points back in second, as well as his three teammates. Castroneves is in third, 22 points behind. Pagenaud is fourth, 34 points back. And Power is fifth, 68 points shy of Newgarden.

“That's why Roger ended up hiring him, he's here because of his talent,” Castroneves said of Newgarden. “He's (been) able to show that the entire season, and then we can see as a teammate what he has brought to the team. He definitely brought a very competitive edge, which is great. At least for me, it keeps pushing me as always.”

Castroneves, whose 30 career wins rank 11th on the all-time list, is still in search of his first series title.

“The goal is to have this championship with Team Penske,” Castroneves said.

Newgarden was asked if having his teammates also in the title hunt will be an advantage or disadvantage on race day.

“They're going to try and beat me just as bad as I'm going to try and beat them, but there's a little bit in the back of the head there that they want to be as fair as possible,” he said. “It doesn't mean they're not going to be hard with the way they race, but you've got to think there's got to be a little bit of fairness with it, too.

“I would say maybe that leans more toward the favorable side, but at the same time, I don't know that it really changes much at the end of the day.”

The GoPro Grand Prix of Sonoma to decide the 2017 championship, airs live from Sonoma Raceway in California at 6:30 p.m. ET Sept. 17 on NBCSN and the Advance Auto Parts INDYCAR Radio Network.