Thorpedo Anna, Nitrogen clash in Spinster

Racing fans won't have to wait until the Nov. 1 Breeders' Cup Distaff (G1) to see a clash of the generations among fillies and mares. That comes Sunday at Keeneland, when reigning Horse of the Year Thorpedo Anna takes on the three-year-old Nitrogen in the $650,000 Spinster (G1) over 1 1/8 miles.

Such a top-heavy edition of the Spinster has resulted in the historic feature attracting only three other starters. But, there's not much use in looking beyond the top two.

Thorpedo Anna hasn't been quite as dominant at four as she was at three, but remains a win machine. After taking her first two starts of the year at Oaklawn Park, she bounced back from a puzzling last-place finish in the La Troienne (G1) to capture both the Fleur de Lis (G2) and Personal Ensign (G1), the latter by a nose over Grade 1 winner Dorth Vader.

For the first time in her career, Thorpedo Anna will be without the services of jockey Brian Hernandez Jr., who was seriously injured at Churchill Downs in late September. Flavien Prat will ride the champion on Sunday.

Nitrogen, meanwhile, has emerged as the nation's leading three-year-old filly, partly by attrition but primarily due to her versatile talents. She's won six of seven this year over turf, dirt, and slop, most recently taking the Alabama (G1) over 1 1/4 miles. A victory in the Spinster would likely sew up championship honors for her, regardless of what happens in the Breeders' Cup Distaff at Del Mar.

Gin Gin and Scylla are Grade 2 or 3 types at best, carrying an equal weight of 125 pounds with Thorpedo Anna. The allowance-class Chilled should follow them all home.

Besides the Spinster, the other Breeders' Cup Challenge race on Sunday's card is the $400,000 Bourbon (G2), a 1 1/16-mile prep for the Breeders' Cup Juvenile Turf (G1). Final Score, dominant winner of the With Anticipation (G3) at Saratoga, appears a solid early favorite for Todd Pletcher. Vintur, who romped on debut by five lengths sprinting at Kentucky Downs, also looms a threat for Mark Casse.

The other stakes with Breeders' Cup implications is the $300,000 Indian Summer S., a 5 1/2-furlong dash that should yield participants for the Breeders' Cup Juvenile Turf Sprint (G1). Sanford (G3) winner Obliteration was second in his turf debut in the Juvenile Sprint at Kentucky Downs last time, while Bobrovsky landed the Skidmore S. at Saratoga when last seen.