LOUISVILLE, Ky. – Easily the deepest turf race in North America so far this year is on tap for Saturday with the Grade 1, $500,000 Woodford Reserve Turf Classic, the main secondary feature on the Kentucky Derby undercard at Churchill Downs.An oversubscribed field of 17 older horses jammed the entry box for the 1 1/8-mile Woodford. The lineup includes such accomplished turfers as Little Mike, Prince Will I Am, Smart Bid, Get Stormy, Doubles Partner, Al Khali, Court Vision, Battle of Hastings, and Expansion.Doubles Partner, winner of the Grade 2 American Turf here last Derby weekend for trainer Todd Pletcher, enters the Woodford off a victory in the Grade 3 Tampa Bay and is 2 for 2 on the Churchill turf.“It’s an extremely tough race, but we like the way our colt is coming up to this, and we know he likes this course,” said Elliott Walden, racing manager for owner WinStar Farm.Only 14 can start, so for the first time, there is an also-eligible list for the Woodford, which will be used in case of any scratches before 4 p.m. Eastern on Friday. Caracortado, cross-entered in the Alysheba on Friday, would be first to make the Woodford off that three-horse list.The Woodford is the richest of the five races that directly precede the Derby in an all-stakes $2 pick six sequence, and it also is the middle leg of the 50-cent Oaks-Woodford-Derby pick three, which was first offered in 2009. The Woodford is the 10th and the Derby is the 11th of 13 Saturday races. The Woodford and the Derby also anchor several other multi-race wagers, all of which figure to attract huge pools.First post Saturday is 10:30 a.m.In the other Saturday stakes:◗ Grade 1, $300,000 Humana Distaff (race 7): Hilda’s Passion, Amen Hallelujah, Evening Jewel, and Shotgun Gulch are the top names for the seven-furlong Humana, perennially a key early-season race in the filly and mare sprint division.Hilda’s Passion, trained by Pletcher, was particularly sharp in Florida this past winter and should go favored when breaking from post 7 in a field of eight. Javier Castellano has the mount.Shotgun Gulch, an Oklahoma-bred, upset the Grade 1 Vinery Madison at Keeneland last month for C.R Trout, with Amen Hallelujah a close second and Evening Jewel fourth.◗ Grade 2, $300,000 Churchill Downs (race 9): This is a sensational betting race, with 12 well-matched older horses, including Aikenite, Apriority, Smiling Tiger, Capt. Candyman Can, Noble’s Promise, and Here Comes Ben, set to go seven furlongs.Aikenite, trained by Pletcher, comes off a resounding victory in the Commonwealth Stakes at Keeneland, while Apriority, trained by David Fawkes, was most recently second in the Carter Handicap.◗ Grade 2, $200,000 Churchill Distaff Turf Mile (race 8): Aruna, winner of the Grade 2 Mrs. Revere over the Churchill turf last fall and unbeaten in three starts in North America, makes her 4-year-old debut as a top contender among 11 fillies and mares in what shapes up as yet another extremely competitive field.Other standouts in an exceptional group include Tapitsfly, winner of the 2009 Breeders’ Cup Juvenile Fillies Turf; Never Retreat, winner of the recent Jenny Wiley at Keeneland; and Upperline, the top filly and mare turfer at Fair Grounds this past winter.◗ Grade 3, $100,000 Twin Spires Turf Sprint (race 6): Chamberlain Bridge, winner of the Breeders’ Cup Turf Sprint here last fall, will try to rebound off a sub-par effort last month at Keeneland when heading a field of nine older horses in this five-furlong dash. Other names of note include Custom for Carlos, Southern Region, and Bridgetown.