Pioneerof the Nile, who won the Grade 1 Santa Anita Derby and three other stakes, has been retired because of a leg injury, according to a statement released on Thursday by his owners, Zayat Stables.\nThe statement said that Pioneerof the Nile suffered "a soft tissue injury to his left front leg." The colt was in training with Bob Baffert at Santa Anita for an expected start in the $300,000 Swaps Stakes at Hollywood Park on July 18 when the injury was detected. No stud plans have been announced.\n"We noticed a little filling in his leg," Baffert said in the statement. "We were hoping he just rapped it. I'm in shock."\nPioneerof the Nile won 5 of 10 starts and $1,634,200.\nBy Empire Maker, Pioneerof the Nile was trained by Bill Mott for much of his 2-year-old season, finishing third in the Breeders' Futurity at Keeneland and fifth in the Breeders' Cup Juvenile in October.\nTransferred to trainer Bob Baffert last fall, Pioneerof the Nile won four stakes from December to April. Last December, Pioneerof the Nile won the Grade 1 CashCall Futurity at Hollywood Park. He was the leading 3-year-old of the Santa Anita winter-spring meeting, winning the Robert Lewis and San Felipe stakes before the Santa Anita Derby.\nPioneerof the Nile had limited success in the Triple Crown, finishing second, by 6 3/4 lengths, to Mine That Bird in the Kentucky Derby, but 11th in the Preakness Stakes on May 16, his final start.