Camelot, the 1-5 favorite, gave trainer Aidan O'Brien his seventh consecutive victory in the 1 1/2-mile Irish Derby yesterday at the Curragh. Joseph O'Brien rode the undefeated colt to a two-length win for his father. Co-owner John Magnier said "it's possible" that the winner of the 2,000 Guineas and Epsom Derby will run in the 1 3/4-mile St. Leger on Sept. 15 at Doncaster, where he could become England's first Triple Crown winner since Nijinsky in 1970.