They slug it out each year at the world's elite horse auctions and continue their blue-blooded battles throughout the European racing season. But the high-profile rivalry between John Magnier and Michael Tabor's Coolmore operation and the Maktoum family's Godolphin Racing stable, which has slowly gained in prominence in North America, will not be renewed in this year's Kentucky Derby (gr. I).Godolphin announced it would be without a Derby representative for the first time since 1999 shortly after its main hope -- Inamorato -- finished third in the 1 1/4-mile UAE Derby (UAE-II). Meanwhile, trainer Aidan O'Brien, the primary caretaker for Magnier and Tabor's stable at Ballydoyle yard, said he would not attempt the Derby this year with his stable of rising stars because of his dissatisfaction with the current quarantine process in Kentucky.North American race fans got their first look at the rivalry that dominates the European racing scene at the 2001 Breeders' Cup at Belmont Park. Godolphin and Ballydoyle horses took home three of the eight championships that day. O'Brien followed with his first crack at the Derby the following year by shipping in 2-year-old champion Johannesburg and Castle Gandolfo from their Ballydoyle base in County Tipperary. However, since Churchill Downs does not have a permanent quarantine facility, both colts were held at Keeneland until being vanned to Churchill Downs the day of the race. Johannesburg finished a disappointing eighth with Castle Gandolfo checking in 12th.When announcing earlier this year Ballydoyle would not be represented in the Derby, O'Brien remained diplomatic but indicated the lack of a quarantine facility was a major factor in the decision."By Churchill Downs not allowing us to quarantine there, it makes things even more difficult," O'Brien told the Blood-Horse. "Last year, they said we didn't give them enough time, but it's been a year and the situation hasn't changed. I don't want to say anything that's going to upset anyone, but we're at a big enough disadavantage just having to travel all that way so early in the year."Officials for Churchill were disappointed by the news, but said there is simply no room on the grounds currently for a facility to be built. Vice president of communications John Asher said setting aside space for a quarantine barn would result in the loss of about 60 stalls. "The first thing we have to do is take care of our local horsemen," he said.But Asher added O'Brien's comments have moved up on the Churchill priority list the development of a quarantine facility."We're looking to find a longer term solution, trying to find space where we could build a suitable facility. But there still is no timetable," Asher said. "We certainly want international participation for the Derby and all our other races. But frankly we didn't see it as a concern until Aidan O'Brien mentioned it."In the past, Godolphin has shipped to Kentucky early enough to quarantine at Keeneland. However, it is O'Brien's custom not to ship his horses until only days before a race, which means they must make the short journey from Keeneland to Churchill Downs the day of the race.In 1992, Churchill converted a warehouse across the street into a quarantine facility for Arazi, the 2-year-old champion in France and North America who was the first Kentucky Derby starter for Godolphin master Sheikh Mohammed bin Rashid al Maktoum. Also that year, the Maktoum family entered Irish stakes-winner Thayer, who finished 13th in the colors of Sheikh Maktoum al Maktoum.The first horse to for Godolphin was Worldly Manner in 1999, a North American-based horse who was purchased privately prior to the Derby for a reported $5 million. He finished seventh. Over the next three year's, Sheikh Mohammed embarked on an experiment to win the Derby by racing Godolphin 2-year-olds in North America, then having them return to the operation's headquarters in Dubai to prep for the Derby. Since that time Godolphin has had four Derby starters, none of which earned a piece of the purse. China Visit and Curule finished sixth and seventh, respectively, in the 2000 Derby; Express Tour was eighth the following year, and Essence of Dubai finished ninth last year. Perhaps Godolphin's best shot at the Derby -- Grade 1-winning Irish-bred Street Cry -- missed the race after suffering an ankle injury while galloping at Churchill Downs.