DUBAI  - Animal Kingdom galloped to a resounding victory in the $10 million Dubai World Cup on Saturday, in the process becoming the ninth American-trained winner in the 18-year history of the world's richest race.Trained by Graham Motion, the five-year-old horse tracked front-running Royal Delta before jockey Joel Rosario sent him clear early in the home straight. He won by two lengths from fast-closing Red Cadeaux, with Planteur replicating his finishing position 12 months ago in third place, a further 4 3/4 lengths in arrears at the end of the 2,000-metre test.For Rosario, victory came on his first ride at Meydan, the state-of-the-art racecourse opened in 2010. "I've never been here before but I knew we had a chance," Rosario said. "I watched a lot of past races and had an idea where we needed to be (through the race)."Victory for Animal Kingdom was just reward for connections of a horse that was due to contest last year's World Cup until he injured a leg three weeks beforehand and was withdrawn. However, Motion was handsomely compensated for his patience with the injury-prone Animal Kingdom, who returned from the 2011 Belmont Stakes with another injury. He had earlier won the Kentucky Derby on just his fourth racecourse start. "I'm numb," Motion said afterwards. "In many ways it was a little like the Kentucky Derby in that he seemed to draw off so easily. I thought it would be a shame if something came and beat him after that."Australia's Arrowfield Stud recently acquired a 75 per cent share in Animal Kingdom from the American entity, Team Valor, and is expected to stand him as a stallion in due course. Before then, Animal Kingdom might take aim at the Royal Ascot meeting in June.Stall 12 had been billed as a possible impediment to Animal Kingdom, who habitually likes to settle in rear before charging home with a late run. However, after a moderate break this time, Rosario took the horse forward so that he emerged from the first bend immediately behind Royal Delta.Godolphin's Hunter's Light, the much-fancied local hope, stalked the pace but raced with too much zest to sustain his effort. He came home in seventh place. As the winner powered clear, Red Cadeaux came out of the pack to claim $2 million for finishing second."This horse never ceases to amaze me," said Red Cadeaux's jockey, Gerald Mosse. "To run second in the Dubai World Cup and get within two lengths of Animal Kingdom, I've got to be happy with that."Victory for Animal Kingdom redressed the balance for American-trained horses, which have suffered a series of disappointments since the World Cup surface was changed from dirt to a synthetic surface three years ago. The horse was already proven on synthetics, having won the 2011 Spiral Stakes at Turfway Park, in Kentucky, ahead of winning the Kentucky Derby.The World Cup was deprived of last year's winner at the eleventh hour when Monterosso was withdrawn in the morning through lameness. Monterosso's intended jockey, Mickael Barzalona, switched to African Story but the combination could only finish fifth in the 12-strong field.In the main supporting race, the $5 million Sheema Classic over 2,400 metres, Japan's Gentildonna threw down a challenge to St Nicholas Abbey, who led early in the home straight, but the Irish challenger ran on too strongly to prevail by 2 1/4 lengths.The winner is trained by Aidan O'Brien for the the long-established partnership comprising Derrick Smith, John Magnier and Michael Tabor, which was also responsible for $1 million UAE Derby winner Lines Of Battle. O'Brien said Lines Of Battle would now be prepared for a tilt at the Kentucky Derby at Churchill Downs.