In the next few days, Jorge Velasquez will win the 4,000th race of his career, making him one of only a dozen jockeys in history to reach that milestone. But if past performances hold, his feat will not be accompanied by much fanfare.

No modern jockey, and possibly no other athlete in any major sport, has accomplished so much while receiving so little public acclaim. Velasquez has recorded 3,995 victories, ridden 11 horses to championships and earned more than $50 million in purses. Yet he has always been outshone by his flamboyant pal, Angel Cordero Jr., and outpublicized by the darlings of the media, Bill Shoemaker and Steve Cauthen. He has never won the Eclipse Award that goes to the outstanding rider each year.

Ironically, the qualities that have kept Velasquez out of the limelight are the same ones that have made him a consistently successful jockey since he came to this country from Panama in 1965.

Some riders habitually win races with flair and drama. Laffit Pincay dazzles aficionados with his raw strength in the stretch run. Cordero displays showmanship even when he dismounts in the winner's circle. Velasquez has quieter virtues. He is like a basketball player who always manages to get open for the easy, unspectacular 10-footer.

He has a keen sense, perhaps more than any other American jockey, of the way a race is developing around him. He almost never gets his mounts into trouble and, remarkably, trouble almost never seems to find him.

"You have to try to anticipate," he said. "In a race, I'm aware of everybody. If there are six or seven horses in front of me, I look to see which rider has the most horse under him. I try to stay close to him, so that when he makes his move I can follow."

In races on the grass, where the sharp turns and congested fields put special demands on a jockey's tactical skills, Velasquez is at his best. He has ridden four of the last 12 American turf champions, most recently Bowl Game, who earned the title by winning the Washington, D.C. International. Bowl Game was only the third-best horse in the field, but when one jockey was blocked and another misjudged the pace, Velasquez got home first with a perfectly timed stretch run.

Yet despite the long list of his successes in major stakes, Velasquez is haunted by thoughts of three races that he hasn't won: the Kentucy Derby, the Preakness and the Belmont.

In 1978, he believed that his time had come: "The best horse I've ever ridden was Alydar. He never gave up; he had such a big heart. We established some kind of a special relationship; he got to know me and I got to know him." Unfortunately, Alydar happended to be born in the same year as the indomitable Affirmed. Alydar's three heart-stopping losses in the Triple Crown series gave him a reputation as the Avis of thoroughbreds, while Velasquez was utterly forgotten amid American's love affair with Affirmed's jockey, Stevie Cauthen.

But while Cauthen's success was flashy and short-lived, Velasquez keeps on winning races with his usual steadiness.

He almost never falls into a slump (even after such frustrations as his losses with Alydar) because he has a formula to halt them. If he has been losing for a few days, Velasquez goes to the stable area every morning, exercises horses, works hard, tells his longtime agent, Vic Gelardi, to redouble his efforts. When the slump is broken, he permits himself to relax.

In the last two years, Velasquez's unflappability was put to the ultimate test. After a Sports Illustrated article alleged that he had helped fix races, and rumors circulated around New York that he, Cordero and others were going to be indicted, his concentration should have been broken and his riding adversely affected. Instead, during the course of 1980, he won 224 races and $5.5 million in purses in his customary quiet fashion.