Horse racing-Kentucky Derby start could prove critical

May 1 (Reuters) - A talented field with a slew of accustomed winners has been assembled for Saturday's Kentucky Derby, and with frontrunners as favorites in a crowded field the start could prove critical. American Pharoah is the early favorite at 5-2 coming off four wins in a row, while stablemate Dortmund, also trained by three-time Derby winner Bob Baffert, is rated a 3-1 pick and coming to Churchill Downs with six wins in six races. Third choice Carpe Diem (8-1), trained by Todd Pletcher, has won four of five career races and co-fourth pick Materiality (12-1) is 3-for-3, bidding to become the first horse to win this race for 3-year-olds without racing as a 2-year-old. The favorites like to run out in front, which could make for a hectic start at Churchill Downs as 19 horses strive to get into favorable position by the first turn. From Baffert's perspective, the Derby will be won, and lost, in the moments after the gates open. "Our horses are not going to be coming from out of the clouds," said Baffert, whose Dortmund drew the eighth position, while American Pharoah starts from the 17th lane. "The break is going to be the key." Riding American Pharoah will be two-time Derby winner Victor Espinoza, who rode last year's champion, California Chrome. "He rides with a lot of confidence and he's been here at the big dance," Baffert said. Martin Garcia has ridden the unbeaten Dortmund for all his races. "This is the first time that he's going to ride a horse that actually has a really good chance to win (the Derby), so I'm sure he will be a little nervous," Baffert said. "He knows his horse. He'll just put him in a nice spot." Sheikh Mohammed bin Khalifa al Maktoum's Mubtaahij, listed at 20-1, won the UAE. Derby by eight lengths and will attempt to win the 'Run for the Roses' without the benefit of a single U.S. prep race. Mubtaahij, who has never been worse than second in his last five starts, would be the first horse to win the Kentucky Derby after racing the UAE Derby. Mark Casse, trainer of Danzig Moon (30-1), hopes the frontrunners will burn themselves out. "I would like to see a fast pace and have us be about 10 lengths behind," Casse said. "Hopefully the pace comes apart at the seams and we can pick them up." (Reporting by Larry Fine in New York; Editing by Peter Rutherford)