It's been 24 years since Seattle Slew became the 10th Triple Crown winner and 17 years since a son of his (Swale) won the Kentucky Derby (gr. I). The Derby arguably is the toughest of all races to win, and any horse who attempts to handle the 1 1/4 miles the first Saturday in May at Churchill Downs against as many as 19 rivals needs a competent trainer and jockey, along with the proper blend of speed and stamina, and a good deal of racing luck. With all that in mind, it's time to take a look at one of Seattle Slew's grandsons, A P Valentine, and see how he fits into the Derby picture.A P Valentine, who scored his big win in the Champagne Stakes (gr. I) last fall, is trained by Nick Zito and was ridden in all four of his 2-year-old races by Jorge Chavez. Zito has won two Derbys, with Strike the Gold in 1991 and Go for Gin in 1994. Zito recently announced that Hall of Fame rider Pat Day will take over as jockey of A P Valentine. Day has had 18 Derby mounts, but only one winner, Lil E. Tee in 1992.A P Valentine's sire, Horse of the Year A.P. Indy, is trying to emulate his half-brother, Summer Squall, with a Derby winner. Summer Squall sired 1999 Derby and Preakness Stakes (gr. I) winner Charismatic.A.P. Indy didn't start in the 1992 Derby because of a quarter crack, but several of his offspring have contested the race and employed contrasting running styles. Pulpit, in the 1997 Derby, and Old Trieste in 1998, both held the lead in the early part of the race, but weakened and finished fourth and 10th, respectively. In the 2000 running, Aptitude came from way back and finished 1 1/2 lengths behind Fusaichi Pegasus in a runner-up effort.Getting back to A.P. Indy, he recovered quickly from the quarter crack and contested the 1 1/2-mile Belmont Stakes (gr. I). He captured that race as the 11-10 favorite and clinched Horse of the Year honors with a triumph in that year's Breeders' Cup Classic (gr. I) at 1 1/4 miles. He stands at William S. Farish's Lane's End Farm near Versailles, Ky.There's also plenty to like about some of A P Valentine's ancestors. His broodmare sire, Alydar, ran second in all three Triple Crown events and sired 1987 Derby/Preakness winner Alysheba, plus Strike the Gold. In A P Valentine's third generation, three of the four stallions are chef-de-race sires -- Secretariat, Raise a Native, and Stage Door Johnny. Triple Crown winner Secretariat and Belmont Stakes winner Stage Door Johnny lean more toward stamina than speed, and Raise a Native's strength in pedigrees leans toward speed. Stage Door Johnny's name in Derby pedigrees popped up earlier as the broodmare sire of Go for Gin.Many racing fans are partial to the dual qualifier system in sorting out Derby contenders, and A P Valentine stacks right up there with the best. Dual qualifiers are those horses weighted within 10 pounds of the male topweight on the Experimental Free Handicap and also have the proper dosage figure to win the Derby. Dosage factors in the presence and position(s) of chef-de-race stallions in a pedigree.A P Valentine was weighted at 124 pounds on the 2000 Experimental, two pounds below highweight and champion Macho Uno, and has a Dosage Index of 1.71 and a Center of Distribution of 0.47. Horses with a DI higher than 4.00 and a CD higher than 1.25 are considered genetically unlikely to win the Run for the Roses. The DI and CD are figured from a Dosage Profile of 10-4-20-2-2. Not all Derby contenders are represented in all five categories, so that's another plus for A P Valentine, who is inbred 4 x 5 x 5 to the great Bold Ruler.A P Valentine's stakes-winning half-brother, Summer Bet, is by Summer Squall, and his dam, Twenty Eight Carat, placed in a restricted stakes. Twenty Eight Caret's half-sister, Erzulie Freda, also is the dam of graded stakes winner Fancy Freda. A P Valentine's fourth dam, Shama (by Bold Ruler), is a half-sister to champion Leallah.A P Valentine was bred in Kentucky by William S. Kilroy and foaled on Valentine's Day in 1998. He races for Rick Pitino's Celtic Pride Stable. Prior to the Breeders' Cup, Irish-based Coolmore Stud bought breeding rights in A P Valentine for a reported $16 million.