American Danica Patrick became the first woman to win a race in the Indy Racing League (IRL) on Sunday, powering to victory in the Indy Japan [Images] 300 race.

The 26-year-old won by almost six seconds from Brazilian Helio Castroneves after the race favourites were forced to pit for fuel in the closing laps in Motegi's Twin Ring Circuit.

"It's been a long time coming -- finally," Patrick told reporters. "This is fabulous. My team called it perfectly for me.

"I knew I was on the same strategy as Helio and when I passed him for the lead I couldn't believe it. My sex has got nothing to do with it. I believed in myself as a driver."

Leader Scott Dixon pitted with five laps to go and Dan Wheldon and Tony Kanaan came in a lap later. Patrick subsequently took the lead from Castroneves with two of the 200 laps left.

Briton Wheldon finished third with Brazilian Kanaan settling for fourth in the third race of the 16-round IRL series.

"I can't say the last stint was exactly hard," Patrick said. "I was taking it easy and going fast but still trying to save fuel.

"All I had to beat was Helio and I knew I had been saving fuel earlier in the stint. I didn't want to make the mistake of not trying harder to get by him."

Patrick had been dubbed the Anna Kournikova [Images] of IndyCar but victory in her 50th start will end comparisons with the Russian pin-up, who quit tennis without a singles title to her name.

"I'm thrilled for her that the monkey is finally off of her back," said Michael Andretti, co-owner of Andretti Green Racing.

"I think this is the first of many. We have all believed in Danica and she proved today that she is a winner."