D.J. Stable’s Nitrogen, one of the leading contenders for divisional honors among 3-year-old fillies, arrived at Keeneland Thursday afternoon and was on the track Friday morning as she continued her preparation for Sunday’s $650,000 Juddmonte Spinster (G1).

The Juddmonte Spinster is a “Win and You’re In” Challenge race for the $2 million Breeders’ Cup Distaff (G1) at Del Mar on Nov. 1. That is where Nitrogen, a multiple graded stakes winner on dirt and grass, is headed.

“I am not putting her back on the grass at this point,” trainer Mark Casse said Friday morning of Nitrogen, who comes into her first test against older fillies and mares off a victory in the Alabama (G1) Presented by Keeneland Sales. “She’s going to run another year.”

Before Nitrogen goes for her Grade 1 victory on Sunday, Casse will send out D.J. Stable, West Point Thoroughbreds and Kenneth Freirich’s undefeated Ewing in Saturday’s $650,000 Claiborne Breeders’ Futurity (G1) going 1 1/16 miles on the main track.

“He is doing well and like everybody else, we will see how he fits going two turns,” Casse said. “It’s a small field (seven entrants), but there is a lot of quality.”