Almost every trainer who spends his life around cheap claiming horses dreams of moving into the upper stratum of the sport, of winning prestigious races, of winning the Kentucky Derby.

But the most successful trainer of claiming horses in America, Jack Van Berg, has no such burning ambition. He has brought his colt Bold Ego to the Derby for the same reasons that he would enter a rock-bottom animal in a $5,000 claiming race. He thinks he can win a purse.

"I'm not here for amusement," Van Berg said. "I don't much like publicity and I'm a poor loser. There won't be any fun if I don't win. And if Bold Ego doesn't finish on the board, I'll be very upset."

Van Berg learned his distinctive style of playing the racing game from his legendary father Marion, who was America's top race-winning owner in 14 different years. "My dad was in the claiming business and spent his own money for horses," Van Berg said. "His stable had to make money. And it did because he was the best horseman who ever lived. He could watch a horse walking down the shed row and see more in two minutes than most trainers see in a week. If it took an hour to rub a horse's leg one morning, you'd rub his leg for an hour. I had the best teacher in the world. Even today, when I have a problem, I try to think about now he would do things.

With the benefit of this tutelage, Van Berg runs an almost unique operation. He has 124 horses in training at five different tracks -- with each outfit supervised by a competent assistant -- and another 60 on his Kentucky farm. He spends almost as much time in airplanes as he does in his stables, jetting around the country to oversee his operations. It is a demanding regimen, but it has paid off; Van Berg has won more races than any other trainer in the country in six of the last 13 years.

But his mode of operation also has gotten him stereotyped. "I hear people say, 'He's just a claiming trainer' and 'You can't give him a classic horse,'" Van Berg said. "Well, I enjoy claiming. When you have a lot of young horses, it gets boring sitting and waiting for them. And if I had 50 or 60 2-year-olds like some of these trainers and only one developed into a top horse, that wouldn't be much gratification. Most of my stakes wins have come with horses I've claimed and have gotten good. But I think I can train a horse as well as any man walkin.'"

Bold Ego is demonstrating the truth of that statement. An unfashionably bred colt from New Mexico, he looked in the early stages of his career as if he were cut out to be strictly a sprinter. A trainer here remembered, "I saw Bold Ego run in California at the start of the year and he fell apart after half a mile. You'd bet a million dollars he'd never go a distance. Then I saw him again this spring winning the Arkansas Derby at a mile and an eighth, and I couldn't believe it. He looked like a different horse. And the difference had to be Jack Van Berg."

After Bold Ego's owners sent him to Van Berg at the start of the year, the colt accomplished things that his prior past performances suggested were highly improbable. He won his first distance race, the Rebel Handicap at Oaklawn, by five lengths, and then led all the way to capture the Arkansas Derby by 1 1/4. He comes into the Derby with earnings of $382.676, more than any other colt in the field.

Bold Ego's presence in this Derby field is especially significant because of his high early speed.He has run a quarter-mile as fast as 21 3/5 seconds, a half-mile in 44 4/5. The favorite in the race, Proud Appeal, is a front-runner, as is highly regarded Cure the Blues. Bold Ego could be the instrument of their destruction. "If they try to go with him, they're going to get nothing," Van Berg said.

The trainer recognizes that Bold Ego could be ruined, too, by a suicidal speed suel or by some of the bad breaks that are inevitable in a field of more than 20 horses. "My dad said he'd take luck over brains any day," Van Berg said. "If we have luck and the good Lord is willing, we'll get the money."