Simon Pagenaud claimed his maiden Verizon IndyCar Series title on Sunday with victory at Sonoma Raceway as title rival and teammate Will Power hit trouble before half-distance.
Pagenaud entered Sunday's title showdown with a 44-point lead over Power in the drivers' championship after taking pole, and managed to retain his lead at the start.
Power moved up from fourth to third at Turn 1 before jumping Penske teammate Helio Castroneves by getting the undercut at the first round of pit stops, leaving only Pagenaud ahead.
Pagenaud was unfazed by having his title rival behind, opening up an eight-second buffer in the lead-up to the second round of stops.
Just before Penske planned to bring the race leader in, the title race took a decisive twist when Power began to slow coming out of Turn 7, as an issue with the clutch control unit reduced him to a crawl on-track.
Power was able to return to the pits under a full course caution, losing seven laps on the leaders at the Penske crew tried to correct the issue on his car.
While the Australian was able to get back out on-track, the damage had already been done, leaving Pagenaud to ease to his fifth win of the season and claim his maiden IndyCar series title.
The championship success comes in Pagenaud's second season with Penske and fifth full campaign in IndyCar, having previously been named as the series' Rookie of the Year back in 2012.
A three-stop strategy combined with some late fuel saving saw Pagenaud cross the line just one second clear of Graham Rahal, who carved into the Frenchman's lead through the final stint but was unable to pass for the lead.
Juan Pablo Montoya rounded out the podium in what looks set to have been his final race for Penske ahead of Ryan Hunter-Reay, while Alexander Rossi sealed the Rookie of the Year award by finishing fifth after running low on fuel on the last lap.
Josef Newgarden finished the race sixth after fending off Helio Castroneves in the final stages, the Brazilian unsuccessfully trying to pull off a four-stop strategy. Marco Andretti enjoyed his best run in recent times to P8, with Charlie Kimball and Sebastien Bourdais rounding out the top 10.