When the nation's best 3-year-olds faced each other for the first time in the Kentucky Derby, Medaglia d'Oro was a highly regarded contender; Came Home had an exemplary record but doubtful stamina; War Emblem was ignored by the experts and the betting public, too.

A lot has happened since War Emblem scored his front-running upset at Churchill Downs. Almost all of the nation's best older horses have been injured, leaving a trio of 3-year-olds as the leading contenders in the Breeders' Cup Classic at Arlington Park. Medaglia d'Oro, coming off two big wins, is highly regarded. Came Home is formidable, too, but some skeptics still doubt his ability at 11/4 miles. And War Emblem is being dismissed by most experts.

While there are many similarities to the Derby, there will be this one difference here Saturday: The stakes are much higher. Not only is the Classic the nation's richest race, with a $4 million purse, but a victory by any of the top 3-year-olds will probably earn him the horse-of-the-year title.

The absence of good older horses makes the Classic a less compelling attraction than usual, and it is quite possible that the star of the Breeders' Cup World Thoroughbred Championships will emerge from one of the other seven races.

* The Mile is expected to be a showcase for Rock of Gibraltar, the European invader who is the most accomplished runner in any of the fields.

The 3-year-old has unleashed his powerful stretch kick to win seven consecutive Grade I stakes, earning him acclaim as a superstar. All he has left to prove is that he can handle an American grass course with tight turns and congested fields -- a significant difference from the long, wide European straightaways that favor his style.

"He's very special," said his trainer, Aidan O'Brien. "He's run in all the Grade I races and he's come out of every one better than the last. He cruises well, he kicks real well -- he's an exceptional horse."

* The Distaff, too, could produce one of the stars of the day, for the field is filled with fillies and mares whose consistency contrasts with the spotty records of the males in the Classic. Azeri, the California-based 4-year-old filly, has recorded nine wins and one second-place in her ten career starts, and trainer Laura De Seroux argues that she is a worthy candidate for the horse-of-the-year title. "Horse of the year implies who has performed the best all year," De Seroux said. "When you're 9 for 10, that's the best performance of any horse this year . . . isn't it?" Despite her imposing record, Azeri faces tough competition from the 3-year-olds Take Charge Lady (8 for 12 lifetime) and Imperial Gesture (6 for 10).

* The Juvenile always attracts special attention because it produces the favorite for the next year's Kentucky Derby, and this year's field appears to be an above-average group. Although the undefeated morning-line favorite Sky Mesa was withdrawn this morning because of an ankle injury, the field of 13 still is very strong, headed by the Bob Baffert-trained Vindication, a $2.15 million yearling who is unbeaten in three starts; Whywhywhy, a winner of three straight stakes in New York; and three superbly bred, O-Brien-trained invaders from Europe.

Even if other races have stronger fields, the Classic remains the cynosure of the day, because the 3-year-olds who have gone through the Triple Crown campaign are the most recognized thoroughbreds in the country. And none has a higher profile than War Emblem.

Since he became a hero with his victories in the Kentucky Derby and the Preakness, War Emblem has been a disappointment, and his last start was a sixth-place finish behind Came Home in the Pacific Classic. Baffert conceded, "That race was disastrous. Everybody has jumped off his bandwagon." Baffert (and everybody else) has recognized that War Emblem needs to have the early lead to run his best race, but he will have trouble outrunning the speedy E Dubai in the Classic.

Medaglia d'Oro will probably be the favorite Saturday, after atoning for his Triple Crown failures by winning a pair of stakes at Saratoga this summer. The support for him is based on respect for trainer Bobby Frankel as much as for the horse's accomplishments. Frankel is a master at brining horses into races fresh, off a layoff, and he believes he has Medaglia d'Oro primed for the race of his life.

Came Home has the best record among the Classic favorites, with six wins in seven starts this season. His only poor effort was his loss in the Derby, which seemed to confirm the suspected shortcomings in his stamina. The colt did win at 11/4 miles in the Pacific Classic, with the aid of an easy trip, and plenty of handicappers still doubt his distance-running ability. But if he can win Saturday, he will finish the year with a glittering record worthy of a Breeders' Cup winner and a horse of the year.

Rock of Gibraltar, dominant Irish 3-year-old, tests the new sod as favorite. "He's very special," Aidan O'Brien said.