Scott Dixon won a thrilling IndyCar finale at Sonoma to beat season-long points leader Juan Pablo Montoya to a fourth series title.
Dixon, entering the final round a distant fourth in the standings, profited from a clash between the Penske team-mates and championship rivals Montoya and Will Power to record his third win of the campaign.
Power actually led the opening 35 laps of the race comfortably, before making his second visit to pitlane under a full course yellow prompted by Luca Filippi, who slowed on track with a throttle sensor problem.
A faultless stop by the Ganassi crew allowed Dixon to crucially jump both Power and Josef Newgarden, with the Australian rejoining ahead of team-mate and title rival Montoya.
Montoya attacked Power off the green flag, only for the pair to collide, the Columbian damaging his front-wing and the latter spinning off the circuit, prompting another caution.
Sebastian Saavedra led briefly under the yellows, as the Penske team-mates pitted for repairs, dropping down to 22nd and 23rd respectively.
The out of sequence Saavedra, Marco Andretti and Oriel Servia, driving the #25 Andretti in place of the late Justin Wilson, all pitted at the end of lap 49, promoting Dixon into the lead for the first time, and handing him the points advantage from Montoya.
Out front, Dixon, with his focus on fuel-saving, controlled the pace during the penultimate stint, pulling clear before his final stop of the year.
The Kiwi looked comfortable out front, ahead of Ryan Hunter-Reay, but all eyes were on Montoya in the closing stages as the Columbian attempted to fight his way back into the fifth position he needed to claim the title.
Contact between Sebastien Bourdais and the struggling Rahal promoted Montoya into sixth, but try as he might, the Penske racer could not catch Ryan Briscoe over the final laps of the season.
As Dixon crossed the line to record back-to-back wins at Sonoma, Montoya was forced to settle for sixth, the pair ending the season tied on 556 points – the title going to Dixon on count back, the Ganassi man with the superior win rate.
Hunter-Reay and Charlie Kimball completed the podium behind Dixon, with Tony Kanaan fourth.
Power recovered to cross the line in seventh, behind Briscoe and team-mate Montoya, to finish third in the drivers’ standings.
Takuma Sato, Rodolfo Gonzalez and IndyCar returnee Mikhail Aleshin rounded out the top 10.
Helio Castroneves slim title hopes were dashed early in the race when he was forced into an early stop for a new nose, and the Brazilian came home a lowly 15th.
It was a difficult finale for Rahal, another championship contender, who was swamped off the start, struggled on his penultimate set of tyres, and was ultimately tipped off the track late on by Bourdais.
Image courtesy of IndyCar Media