Forty-eight hours ago, the outlook for the Kentucky Derby was indecipherable. The country's best 3-year-olds seemed to have questionable stamina or physical condition, and dozens of horses were considered candidate for a wide-open Derby.

But the Gotham Stakes at Aqueduct on Sunday was a revelation. It was one of the best horse races I have even seen, and it suggested that both Proud Appeal and Cure the Blues -- who finnished a nose apart -- may be bona fide superhorses. Instead of being compared with the country's other 3-year-olds, they should be compared with past champions like Seattle Slew and Affirmed. No other Derby aspirants are in their league.

The two colts battled for every step of the mile race, straining and struggling for every inch advantage before Proud Appeal won by inches at the wire. They proved not only that they possess great competitive spirit, but also sheer, raw speed. Proud Appeal and Cure the Blues sped a half-mile in 45 seconds, three-quarters in 1:08 4/5, a mile in 1:33 3/5. According to my speed figures, they ran faster than any Kentucky Derby winner in the past decade has in any of his prep races.

The two ought to dominate the Kentucky Derby and the Triple Crown series, unless they self-destruct or destroy each other. And that is a possibility.

The kind of race that Proud Appeal and Cure the Blues ran on Sunday has to enervate the best-conditioned of thoroughbreds.After they recover from the stress of that race, they will have to do it all over again in the mile-and-one-eighth Wood Memorial Stakes on April 18. And then again in the Derby.Such stress must take a toll.

Racing fans will remember that Affirmed and Alydar withstood a series of memorable duels in 1978, but they were different types of horses. Their jockeys could rate them, and the arch rivals could lope alongside each other until they started running in earnest for the last half-mile. Neither Proud Appeal nor Cure the Blues seems to have this sort of tractability. Their trainers will have to harness their speed and competitiveness to some extent, because horses don't win the Kentucky Derby after battling head-and-head through a half-mile in 45 seconds.

But even if a case could be made against Proud Appeal and Cure the Blues, it is difficult to make a strong case now for any of the horses who are likely to challenge them at Churchill Downs.

Tap Shoes, the winner of the Flamingo Stakes at Hialeah, is considered a principal Derby contender, but he is grossly overrated. He ran slowly and beat a bad field in Florida; he couldn't have come within a dozen lengths of Proud Appeal on Sunday. If he wins the Derby I'll burn my speed figures.

West Coast chauvenists are trumpeting the virtues of Flying Nashua, who will be the favorite in the rich Santa Anita Derby next Sunday. But he looked good while finishing fast in the San Felipe Handicap last week only because he was running against such an undistinguished bunch of horses. The only gifted 3-year-old on the West ycoast this year was Lemhi Gold, who won his racing debut sensationally, but subsequently bucked his shins and will be out of action for months.

Highland Blade is probably the strongest stretch-runner among the Derby contenders. He had raced mostly on the grass until trainer David Whiteley gave his a chance on the main track in the Everglades Stakes at Hialeah. The colt finished explosively to win it and since then Whiteley has been pointing him for the Wood Memorial. Until Sunday, he had figured to be a strong contender in that race. Now it seems he will be little more than a foil for Cure the Blues and Proud Appeal.