Colton Herta became the youngest winner in IndyCar history after taking a shock victory for Harding Steinbrenner Racing in the inaugural IndyCar Classic at the Circuit of The Americas on Sunday.

In only his third IndyCar race start, Herta was able to cycle to the front of the field after a caution period called following his final pit stop at COTA before pulling clear of Penske's Josef Newgarden in the final 10-lap sprint to the flag.

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Herta crossed the line 2.7 seconds clear of Newgarden to break Graham Rahal's record and become the youngest winner in IndyCar history at the age of 18 years and 11 months.

Herta started the race fourth for Harding Steinbrenner Racing but made a good start to run as high as second early on, keeping pace with pole-sitter Will Power and Andretti Autosport's Alexander Rossi.

Power and Rossi ran within a second of each other at the front of the pack nearing the final round of pit stops, but both were caught out when a crash for Felix Rosenqvist triggered a full course caution. With the pit lane shut until the field had bunched up behind the Safety Car, Rossi was forced to drop down the order, while Power retired after stalling his car when trying to pull out of his pit box.

Herta benefitted from the caution after making his final pit stop before Rosenqvist's crash, leaving him at the head of the pack for the restart with 10 laps to go.

Despite having less than half of Newgarden's push-to-pass boost remaining, Herta was able to nail his restart before pulling clear of Newgarden, extending his advantage to more than two seconds in the space of a lap.

With Newgarden left soaking up pressure from Ryan Hunter-Reay behind, Herta was able to round out the closing laps before crossing the line to become COTA's maiden IndyCar victor and the series' first driver born in the 21st century to win a race.

Newgarden held on to second place ahead of Hunter-Reay in third, with Graham Rahal finishing fourth. Rahal was one of the first drivers to congratulate Herta in victory lane after the chequered flag.

Sebastien Bourdais and Marco Andretti both cashed in on the late caution to rise to fifth and sixth respectively ahead of Takuma Sato, while Patricio O'Ward put an impressive display to take eighth on his second IndyCar start.

Rossi could only take ninth for Andretti after fighting up the order in the closing stages of the race, making a final lap pass on Jack Harvey, who rounded out the top 10.