It's the shamrock and St. Patrick, the crescent moon and the prophet Mohammed. One land is cool and wet, the other hot and dry. A visitor to an Irish race meeting might think the flamboyant Celts love nothing as much as gambling and boozing, activities forbidden to Muslims. It would be hard to find two nations with as little in common, except for the passion for the thoroughbred. Ireland and Dubai connect only in the shared obsession of Coolmore and Godolphin to rule that world.

These titans have spent billions and spared no effort in relentless quests to acquire the best bloodstock to win classics everywhere. For years John Magnier's conglomerate and Sheikh Mohammed bin Rashid al Maktoum's empire have staged epic bidding wars at auctions in Keeneland and Saratoga. Their heavyweight champions slug it out in the greatest races around the globe, and when one doesn't win, the other usually does.

Yet there is one marquee event where neither has conquered, and late Saturday afternoon the Godolphin and Coolmore colors will face off in the 128th Kentucky Derby. For the fourth consecutive year, Godolphin will be part of America's Race. For Coolmore, it's new. Neither will be favored, and neither has any illusions of what it's up against.

"The main race we think to win is the Kentucky Derby," said trainer Saeed bin Suroor, who will saddle Godolphin's Essence of Dubai. "It is the most difficult race in the world, and the best race in the world."

Michael Tabor co-owns last year's Breeders' Cup Juvenile winner, Johannesburg, with Magnier's wife, Susan. Tabor owned 1995 Kentucky Derby winner Thunder Gulch, which he said "whetted his appetite" to repeat the feat. Trainer Aidan O'Brien also will send out Castle Gandolfo for Coolmore. He's run only once on dirt, winning a minor stakes April 6 in England over Lingfield's all-weather surface.

"The thought of going to Kentucky is a thrilling challenge," Tabor said Tuesday. "[Johannesburg] is Europe's horse. He's the champion of Europe, and he's trying to win the biggest race in America. But in all walks of life, it's very hard to win away from home. If one of the American horses came over to race in England or Ireland, it would be very difficult for him to win."

There is virtually no interest among Americans to try for the Epsom Derby or the Prix de l'Arc de Triomphe. Yet for Coolmore and Godolphin, succeeding on a grand scale in the United States is high on their agendas. Godolphin got off an 0-for-13 schneid in the Breeders' Cup when Daylami won the Turf in 1999 at Gulfstream. Last year it scored with Tempera in the Juvenile Fillies and Fantastic Light in the Turf and missed by a nose with Sakhee in the Classic. Only Johannesburg has won for Coolmore at the Breeders' Cup.

Even the superpowers need time to learn new tricks. Godolphin has never done better than sixth with its four Derby entries. "Before, we ran horses that were not good enough to win or could not stay the distance," Suroor said. "I learned you have to bring a horse that has class and can stay [1 1/4 miles]."

Suroor thinks Essence of Dubai has the quality and foundation to make a breakthrough. He won a stakes last year at Santa Anita before running last in the Juvenile. After two preps in Dubai, he'll have trained for more than two weeks in Louisville. Unlike his rivals, his staying power is not an issue. His come-from-behind victory in the 1 1/4-mile United Arab Emirates Derby makes him the first horse since 1971 to enter the Kentucky Derby with a win at 10 furlongs.

"He has won at the distance and we think he likes the ground [at Churchill Downs]," Suroor said. "He has a good action over the dirt. He is the best we have brought over. He is a tough horse, and honest in his work. He does get sweated up and nervous, but I hope he becomes relaxed before the race. We work hard to bring the best horse to the Kentucky Derby. I think this time we have brought over the right one. We hope we'll get a better result than before."

Unlike Essence of Dubai, Johannesburg never has run around two turns or beyond 1 1/16 miles. He has had only one prep and his pedigree is slanted toward speed. Is he a terrific sprinter/miler being asked to go too far?

"Well, obviously [stamina] is the big question mark," Tabor said. "But then I suppose if the pedigree experts were correct all the time, it wouldn't be a game. They are correct on many occasions, and maybe they will be on this. But those experts probably would have been dubious about him running in the Breeders' Cup at a mile and a sixteenth, I presume.

"Now we know this is a different kettle of fish, that two turns and one and a quarter miles is a vast difference from the one-turn mile and a sixteenth. But we just have to take our chance. It is just one of those things which you don't know until you try to do it."

Johannesburg's reputation took a hit April 7 when he lost for the first time in seven races after the 4-year-old filly Rebelline caught him in the final strides of the 7-furlong Gladness Stakes on the Curragh's soft turf.

"My immediate reaction was I was certainly pretty sick that he got beat," Tabor said. "Then two or three days later, after having spoken to Aidan and John Magnier, I wasn't so sick. Because Aidan said he needed the race badly, and that he'll come on a lot for the race. The conditions weren't ideal, and horses get beaten. So while I would have hoped that he would keep his 100-percent record, it wasn't to be, and we just hope for the best now."

Godolphin has been paying its Derby dues since 1999, and there are some expectations for Essence of Dubai. Coolmore's first try is more of a reconnaissance mission than a serious assault. If Johannesburg and Castle Gandolfo finish up the track, it will be more like growing pains than failure.

"[Johannesburg] could have gone for the English 2,000 Guineas, but there is only one Kentucky Derby ... I've got every confidence in Aidan. I mean, look at his record. But he doesn't have deep experience of American racing and of the Kentucky Derby. It's a learning curve, and I'm sure he will learn a lot from this. But you've got to start from somewhere."

When asked about Coolmore's rivalry with Godolphin, Tabor stressed that it's mainly business. "I think it's just really they are our main competition," he said. "It is certainly not personal. I'm sure they love to beat us and we certainly love to beat them. But at the end of the day, we know we're not going to win all the time, and vice versa."

Both sides handle victory and defeat with remarkable grace, but seeing the other's horse draped with roses would test that self-restraint severely. Congratulations would not be heartfelt. When two international giants seek the same prize, if one gets it, the other loses more than a race.