There is no question about the identity of the fastest racehorse in America. His name is Phone Trick, and he may well be the best sprinter of the decade.

With his victory in the True North Handicap at Belmont Park on Sunday, Phone Trick remained unbeaten in nine career starts. Only two horses have ever finished within a length of him. The 4-year-old has dominated his competition in both California and New York. He has run a quarter-mile in 21 seconds flat, three-quarters of a mile in an amazing 1:08.

Phone Trick is not only endowed with blazing speed, but he is blessed with good fortune, for he came along at a time when the Breeders' Cup has made it profitable to be a great sprinter.

As recently as 1983 there were only two sprints in the country that offered purses of $100,000, so the trainer of a horse such as Phone Trick had to try to get him to go longer distances if he wanted to make big money. But because of the existence of the $1 million Breeders' Cup Sprint, Dick Mandella can let Phone Trick do what comes naturally.

"This horse is a natural sprinter," Mandella said. "He looked like a star right off the bat. I bought him at a 2-year-old sale for $85,000 -- which was a lot of money for his pedigree -- but he looked like a standout. And when I put him in training, he was a professional right from the start. The first time he ran he went six furlongs in 1:09 1/5."

Phone Trick won his first four races as a 3-year-old and looked like the long-range favorite for last year's Breeders' Cup Sprint until a knee injury sidelined him for several months.

But he was just as sharp when he returned to competition and, after he had won his first seven starts, the only possible knock against him was that he had done all his running in California, where the rock-hard tracks traditionally favor speed horses.

But Phone Trick came east for a stake at Aqueduct in April, and he erased any doubts about his brilliance. On a day when the track wasn't particularly fast, when the best filly sprinters in New York went six furlongs in 1:11 and high-class allowance horses went in 1:11 2/5, Phone Trick sped the distance in 1:08 4/5.

For speed handicappers, his figure went into the stratosphere. It was the kind of figure that even such horses as Secretariat and Seattle Slew ran only on their best days, and it verified that Phone Trick would be a star in any year, at any track.

His jockey, Jorge Velasquez, felt the same way. "I've been riding for 23 years and I've never been on a better sprinter," Velasquez said.

Mandella had hoped to test Phone Trick's distance capabilities by running him in the one-mile Metropolitan Handicap last month, but when a foot infection interrupted the colt's schedule, the trainer had to change his plans.

"I do think he'll go a route of ground at some time," Mandella said. "And if he does win a race at a distance, he will be worth a lot more money when he goes to stud. But we're not going to try it this year. It's too risky to take a chance upsetting what I've got -- and what I've got is a sprint champion."