Godolphin's Breeders' Cup Classic (gr. I) runner-up Sakhee heads a list of 56 horses nominated to the Maktoum Challenge Series, a three-race series of dirt races at Nad al Sheba which also serve as prep races for the Dubai World Cup (UAE-I).The series kicks off Jan. 17 with a one-mile race, and continues with a 1 1/8-mile race and a 1 1/4-mile race on Feb. 7 and 28, respectively. The Dubai World Cup will be run on March 23.Godolphin holds a strong hand with nominees Tobougg, E Dubai, Street Cry, and Noverre, in addition to Prix de l'Arc de Triomphe (Fr-I) winner Sakhee and others. China Visit and Best of the Bests, who each won a leg of the series last year, are nominated again this year.Hamdan al Maktoum's Dubai Champion Stakes (Eng-I) Nayef, who closed 2001 with a four-race winning streak for trainer Marcus Tregoning is also nominated.Horses are awarded points based on finishing positions in the three races. The winner must have raced in more than one event.