After the win, Patrick repeatedly credited Moyer with the call to come in and top off on the 150th lap. The leaders had all pitted shortly after a yellow for a crash by Roger Yasukawa on the 142nd lap, but Patrick, Castroneves and Carpenter all came in one more time during the caution.

“I did feel like it was fast near the end, and I was managing to keep the speed up while saving fuel,” Patrick said. “I heard from Kyle that all I needed to beat was Helio. I knew during that last stint I’d been saving a little more than he had. I knew he was the one to beat, but I didn’t want to make the mistake of not pushing hard enough to get by him.”

Castroneves held on for second to keep the IndyCar Series lead by 12 points over Dixon, who finished third. Wheldon was fourth, Kanaan fifth, Carpenter sixth and Ryan Hunter-Reay seventh.

Patrick is overwhelmed with emotion: first win comes on fourth year of IndyCar competition. (LAT Photo) » More Photos

Dixon appeared to be in position to win but knew he’d have to pit before the end of the race. The only hope was that the drivers who tried the late top-off wouldn’t have enough to get to the finish line ahead of him.

“When you're leading or you're in front of the next competitor that's on the same strategy, you're the sitting duck,” Dixon said. “Nine times out of 10, you're going to lose it. But we did our best today, and I think we had a fast car, and we just came up short.”

When the champagne had been sprayed and everyone had been thanked, Patrick realized that she had achieved a moment in sports history, one that she had anticipated and wanted for a long time.

“It may have been a little anticlimactic,” she said. “It was kind of like, ‘It happened.’ Then I was like, ‘Yea! Did it really happen? I'm first for sure?’ And then obviously the emotion came out.”

Following Sunday’s Champ Car finale at Long Beach, the IndyCar Series resumes next weekend at Kansas Speedway.

Indy Japan 300 results:

1) Danica Patrick, Andretti Green, 200 laps
2) Helio Castroneves, Penske, 200, +5.8594 seconds
3) Scott Dixon, Target Ganassi, 200
4) Dan Wheldon, Target Ganassi, 200
5) Tony Kanaan, Andretti Green, 200
6) Ed Carpenter Vision, 200
7) Ryan Hunter-Reay, Rahal Letterman, 200
8) Darren Manning, Foyt, 199
9) Ryan Briscoe, Penske, 199
10) Townsend Bell, Dreyer & Reinbold, 199
11) Hideki Mutoh, Andretti Green, 199
12) Buddy Rice, Dreyer & Reinbold, 198
13) Jay Howard, Roth, 192
14) Roger Yasukawa, Beck, 134, mechanical
15) A.J. Foyt IV, Vision, 103, accident
16) Vitor Meira, Panther, 92, accident
17) Marty Roth, Roth, 44, accident
18) Marco Andretti, Andretti Green, 0, accident