Some of the top fillies and mares in training have been entered in Sunday's $500,000 Juddmonte Spinster Stakes (gr. I), the fourth of four grade I stakes on opening weekend at Keeneland in Lexington.The Spinster, at 1 1/8 miles, will be run for the first time on Polytrack. Only two members of the field--Horton Stable's Lemons Forever and Farish and Kilroy's Soul Search--have raced on Polytrack, and both have wins on the Turfway Park surface. Soul Search scratched from last week's Turfway Park Breeders' Cup Handicap (gr. III) to try the Spinster.Lemons Forever, trained by Dallas Stewart, broke her maiden at Turfway last fall, and this spring finished a close third in the Bourbonette Breeders' Cup Stakes (gr. III) at the Northern Kentucky track. In her next start, the Lemon Drop Kid filly won the Kentucky Oaks (gr. I) at Churchill Downs with a last-to-first move.Since then, Lemons Forever has finished fourth twice and third once in grade I stakes for 3-year-old fillies in New York. She is the only 3-year-old in the field of nine entered in the Spinster.Favoritism could fall to Stronach Stable's Spun Sugar, who's three-for-four this year with two grade I victories--the Apple Blossom Handicap at Oaklawn Park and the Go For Wand Handicap at Saratoga. Trained by Todd Pletcher, 4-year-old Spun Sugar, by Awesome Again, will make her Polytrack debut off a series of works at Saratoga.Stewart Madison's Happy Ticket, who just failed to defeat Spun Sugar in the Apple Blossom, is scheduled to make her first start since early August for trainer Andrew Leggio Jr. The 5-year-old Anet mare is a multiple graded stakes winner who has been training regularly at Harrah's Louisiana Downs in preparation for her return.An intriguing entrant is Martin Schwartz's Asi Siempre, a 4-year-old El Prado filly that has started 14 times, with all starts on the grass. Asi Siempre last summer finished second in a grade I turf stakes in her United States debut, and last fall won the grade III Valley View Stakes on the grass at Keeneland.Asi Siempre has been working well at Turfway, where trainer Patrick Biancone has a large string of horses, for her Polytrack racing debut.Others in the Spinster line-up are Everest Stables' Island Escape, who has raced primarily on the turf this year; Promenade Girl, winner of the Molly Pitcher Breeders' Cup Handicap (gr. II) at Monmouth Park in her last start; Summerly, winner of the 2005 Kentucky Oaks; and Sharp Lisa, winner of the grade II Santa Barbara Handicap on the grass at Santa Anita Park this spring.Here's the field in post-position order with jockeys, trainers, and weights (pounds):1. Happy Ticket Garrett Gomez Andrew Leggio Jr. 123 2. Island Escape Jesus Castanon Nick Canani 123 3. Promenade Girl Jeremy Rose Lawrence Murray 123 4. Spun Sugar Mike Luzzi Todd Pletcher 123 5. Summerly Shaun Bridgmohan Scott Blasi 123 6. Asi Siempre Julien Leparoux Patrick Biancone 123 7. Sharp Lisa Rafael Bejarano Doug O'Neill 123 8. Soul Search Robby Albarado Neil Howard 123 9. Lemons Forever Mark Guidry Dallas Stewart 120Post time for the Spinster is set for 4:45 p.m. EDT as the eighth race on a nine-race program. Co-feature of the afternoon is the $100,000 Woodford Stakes at 5 1/2 furlongs on the turf. The race drew a full field of 12 with one also-eligible.