In three decades of covering horse racing, I have witnessed many of the sport's most historic and dramatic events:

* The Easy Goer-Sunday Silence rivalry of 1989, culminated by their epic battle in the Breeders' Cup Classic;

* The Affirmed-Alydar battles of 1978;

* Secretariat's 31-length victory in the 1973 Belmont Stakes that completed his sweep of the Triple Crown--probably the greatest single performance by a thoroughbred.

Yet the event that engaged and excited me more than any other was Canonero II's pursuit of the Triple Crown in 1971. It began with one of the most shocking, inexplicable upsets of all time and ended with one of the most ebullient scenes ever seen at an American track.

If a horse with Canonero's record had appeared in a run-of-the-mill claiming race, most handicappers would have paid him little attention. The colt had an undistinguished record in Venezuela, and racing in that country isn't major league even by South American standards.

Moreover, his trip to the United States was a series of misadventures that included a three-day delay in quarantine and a 20-hour van trip to Louisville. His only workout at Churchill Downs was a ridiculously slow half mile in 53 seconds. If he hadn't been part of a six-horse mutuel field, he would justifiably have been 100 to 1. Yet Canonero delivered a stunning performance; he came from 18th place, swooped powerfully around the 20-horse field and won in a runaway.

Rarely has a Derby winner been greeted with such skepticism--even derision. Plenty of experts predicted that Canonero would never win another race. When the colt came to Pimlico, reports circulated that he was lame, and the rumors were hardly quieted when Canonero worked five furlongs in a laughable 1 minute 5 1/5 seconds to prepare for the Preakness.

I watched the workout with trainer Juan Arias and (because the trainer spoke no English) gave him a quizzical look after the slow move. His one-word reply: "Perfecto." This little-known trainer was a man who marched to the sound of a different drummer.

Not only were there doubts about Canonero's fitness, but also about his style. After rallying from far behind at Churchill Downs, he was now about to run on a Pimlico track legendary for favoring speed horses. Everybody assumed that Canonero was a pure stretch-runner. And nobody asked Arias if Canonero could change his style to adjust to Pimlico.

I still remember the start of that Preakness as the most electrifying moment of any big race I have covered. Eastern Fleet, the fastest American 3-year-old, shot to the lead, as expected, but Canonero flashed from the gate and challenged him.

The two colts ran head-and-head around the track, sprinting five lengths away from the rest of the field, covering the first six furlongs in 1:10 2/5--a fast pace that should have enervated both of them. It didn't. Canonero inched away in the stretch and won in track-record time.

Suddenly, Canonero was a popular rags-to-riches hero. With a Spanish-speaking owner, trainer and jockey, he was the darling of Hispanic fans, who turned out in force at Belmont Park when Canonero attempted to become the first Triple Crown winner in 23 years. The crowd of 82,694 is still the largest to see a race in New York, and it was hardly a typical racetrack crowd. Fans danced in the grandstand to the sound of guitars, punctuating their movements with shouts of "Viva Canonero!" They formed conga lines and danced from floor to floor of the staid racetrack.

They let out a deafening roar when jockey Gustavo Avila sent Canonero to the front and opened a 2 1/2-length lead. But when he turned for home, the party was over. He faded and finished fourth--possibly the victim of a foot infection that disrupted his training before the Belmont.

Canonero was no fluke. Sold to a prominent American stable, he came back as a 4-year-old to set a track record at Belmont Park while trouncing Kentucky Derby winner Riva Ridge. Retired at the end of 1972, he was unsuccessful as a stallion before he died in 1981. But nobody who watched his Triple Crown campaign will forget him.

Andrew Beyer first covered sports for The Washington Post from 1966 to '70 and returned in 1978.

CAPTION: After an undistinguished record in Venezuela, Canonero came within win of 1971 Triple Crown.