MADISON, Illinois – While he was leading the Bommarito Automotive Group 500 presented by Valvoline, Helio Castroneves reached a career milestone. By the end of the race under the lights at Gateway Motorsports Park, it didn’t matter to him.

Castroneves reached 6,000 laps led in his career – fourth highest in Indy car history – but he wasn’t able to forgive himself for a mistake in the pits Saturday night that cost him a chance at victory.

Castroneves’ No. 3 Shell Fuel Rewards Team Penske Chevrolet stalled during a pit stop on Lap 157. At the time, Castroneves had pitted from the lead under green. By the time the field cycled through its pit stops a few laps later, Team Penske teammate Josef Newgarden was in first place and Castroneves in fourth.

Newgarden went on to win the race and maintain his lead in the Verizon IndyCar Series standings with two races remaining in the 2017 season. Castroneves finished fourth and held third in the standings, 42 points behind Newgarden and 11 points behind Scott Dixon of Chip Ganassi Racing.

In the pits after the race, Castroneves expressed his dejection.

“It could have been much worse,” said Castroneves, winner of the most recent Indy car race at Gateway in 2003. “But in a situation like that, small mistakes can cost big in the end. This wasn’t just a small mistake; it was a big mistake.”

Castroneves said the car’s engine sputtered and stalled as he was about to leave the pit stall. The crew restarted it and got Castroneves back in the race, but he couldn’t make up ground on Newgarden, Dixon or teammate Simon Pagenaud.

“The team did a phenomenal job to get me in front,” Castroneves said. “The car was incredible. I’m so disappointed. The boys did an incredible job. I’m just so disappointed in myself.”

The impetus for the disappointment lies in the details of Castroneves’ 20-year career. In spite of 30 career victories, three Indianapolis 500 wins and four runner-up finishes in the championship – and trailing only Mario Andretti, A.J. Foyt and Michael Andretti in all-time laps led – Castroneves has yet to win a season championship.

“I’m super disappointed, especially at this stage of the championship,” he said. “It’s not even a small mistake. It’s a huge mistake. I’m so disappointed.”

Castroneves will try to make amends this week when the Verizon IndyCar Series heads to Watkins Glen International for the INDYCAR Grand Prix at The Glen. The 42-year-old Brazilian has never won on the historic 3.37-mile permanent road course, his third-place showing a year ago his best finish in seven tries there.

Live race coverage from Watkins Glen begins at 1 p.m. Sept. 3 on NBCSN and the Advance Auto Parts INDYCAR Radio Network.