While the outcome of the Preakness Stakes was controversial, there was no question that Linda Zang won the Grand Prix Special yesterday at the Potomac Horse Center dressage competition, a screening trial for the United States equestrian team.

Zang, 34, of Davidsonville, Md., scored 63.17 percent on her Swedish half-bred, Fellow Traveler. Edith Master of Chester, N.J., on Dahlwitz, had final average of 60.83.

Zang's victory assures her the opportunity for further evaluation next week at team headquarters in Gladstone N.J. All riders who scored 58 percent or better during the two days of competition -- which is scored like figure skating, with each intricate movement given a numerical grade -- will perform at Gladstone.

"I was bound and determined to do this," said Zang, who never stopped smiling during her performance.

John Winnett of Tuxedo Park, N.Y., who won the first day of competition on his horse Leopardi, placed third at 59.83 percent. Lendon Gray of Dixmont, Maine, was fourth on Beppo with 59.42 percent.

At Gladstone, six dressage riders and six horses will be selected to represent the United States in international competition in Europe this summer.

Six riders and 16 horses from the jumping team and another six from the three-day team will join them on the tour.