LOUISVILLE, Ky. — The girl was on horses before she could walk and grew up following her mother around barns in her native New Jersey. She quickly grew out of pony racing and into thoroughbreds, first galloping horses in the mornings on Maryland racetracks. She got a jockey’s license when she was 17 and earned her first victory with her first mount, Ringofdiamonds, on June 9, 2005.

To get horses, she rode under the name A. R. Napravnik.

“I didn’t want anyone to know I was a girl,” Anna Rose Napravnik said.

More than 1,000 victories later, Rosie Napravnik will be aboard Pants on Fire on Saturday for the 137th running of the Kentucky Derby, only the sixth female jockey in the Derby’s history. She has already become the first woman to win the Louisiana Derby, with Pants on Fire, and is intent to show that neither she nor her colt are mere historical footnotes.

“I got a live mount, and I’m an accomplished rider,” the 23-year-old Napravnik said. “I know the racetrack is still a man’s world. Every day I hear a trainer or owner say ‘I don’t want to ride a girl or you’re not strong enough.’ But I also can tell you I’m riding horses now for a lot of those guys I heard it from.”