DUBAI, United Arab Emirates – It’s probably fair to say that at this stage of his career – one of the best careers in racehorse-training history – Aidan O’Brien can live without winning the Kentucky Derby. On the other hand, it’s probably fair to say he wouldn’t say no to the experience. O’Brien has run five horses in four Kentucky Derbies. :: ROAD TO THE KENTUCKY DERBY: Prep races, point standings, replays, and analysis The best of them was Johannesburg, who had shipped to Belmont Park the autumn before and won the Breeders’ Cup Juvenile. As a 3-year-old of 2002, Johannesburg got in a seven-furlong prep race at The Curragh in Ireland, shipped to Churchill Downs, and finished eighth in War Emblem’s Derby. Johannesburg, it turned out, was an early-developing miler type, not suited to the Derby. The best finish among O’Brien’s Derby horses was by Master of Hounds, who managed a fifth behind victorious Animal Kingdom in 2011. He was a one-time winner before shipping to Churchill Downs, and he went on to win the Group 1 Jebel Hatta over the Tapeta surface at Meydan as well as a Group 2 in Turkey. :: Get PPs for the Dubai World Cup, click here and choose "Meydan"  O’Brien’s other Derby starters were Castle Gandolfo (12th in 2002), Daddy Long Legs (did not complete the course in 2012), and Lines of Battle (seventh in 2013). Thirty-some days away from Kentucky Derby 2018, it appears O’Brien has his best chance yet for the Derby with Mendelssohn. First things first: Mendelssohn must earn his way into the Derby on Saturday night at Meydan Racecourse when he starts in the Group 2, $2 million UAE Derby. Churchill Downs determines the 20 Derby starting slots through three series of races that award points to the top four finishers. Eighteen of those races, including the UAE Derby, are part of the main Road to the Kentucky Derby, and a first- or second-place finish, worth 100 and 40 points, all but assures a Kentucky Derby spot. :: Just reduced! Save on The Road to the Kentucky Derby Player's Package Mendelssohn already has 20 points on the European Road to the Kentucky Derby – which is meant to produce one Derby starter – having won the Patton Stakes on March 9 at Dundalk in Ireland. But Gronkowski also has 20 points, and all he has to do is finish fourth or better Friday in the Burradon Stakes to claim the Derby slot allotted to the European series points leader. So Mendelssohn cannot afford a misstep Saturday if he is to make it to Churchill Downs, but O’Brien has an excellent record in the UAE Derby. Two of his three Dubai wins have come in the race, and Master of Hounds was beaten a nose here before going on to Louisville. “Hopefully, if everything goes well, he’ll be able to go on to Kentucky,” O’Brien said last week, reached at his home base of Ballydoyle in Ireland. “Everything has gone well since Dundalk.” O’Brien won’t just come out and say it, but he lays out the puzzle pieces that, when assembled, show a horse with a more reasonable Derby hope than anything he has trained before. Mendelssohn is the most accomplished horse O’Brien has considered for the American Triple Crown since Johannesburg. He was a fine second in the Group 1 Dewhurst Stakes before traveling to California and winning the Breeders’ Cup Juvenile Turf. Then there is the pedigree. Mendelssohn is by Scat Daddy and out of the Tricky Creek mare Leslie’s Lady. The pedigree leans to dirt generally, and in particular, Mendelssohn’s sister is the great dirt mare Beholder. “He’s a little bit different than the others pedigree-wise,” O’Brien said. “Physically, he’s also a little different. Johannesburg was not as big and strong; Master and Hounds was maybe a little more angular. He travels well, too, which we know is a necessity.” And finally, unlike O’Brien’s previous Derby candidates, Mendelssohn would come to Churchill Downs with two preparatory races instead of one. But first, he has to get there