The Washington Diplomats, looking to put a stop to a five-game losing streak, have obtained a top midfielder in Cus Hiddink from Holland. The 6-foot, 175-pound Dutchman, a first-division player with Nec, will start at the left midfield tonight when Washington plays the Vancouver Whitecaps at RFK Stadium at 8.

The Whitecaps, 10-5 with 83 points, need a win to stay close to Portland, 11-4 and 91 points, which leads the Western Division of the National Conference.

Vancouver beat Washington. 2-1, two weeks ago but will be without midfielder John Sammels and forward Kevin Hector, its leading scorer.

The Dips. meanwhile, are coming off a disappointing 1-0 loss Wednesday to the Hurricane in Houston. That performance deeply distressed Washington Coach Gordon Bradley.

"The Houston game was our worst of the season," he said. "Vast improvement is necessary if we are to get back to playing the way we were earlier this season.

Bradley is hopeful that Hiddink can help turn around the Dips.

"Cus is an established star in Dutch soccer and has the necessary skills and experience to make our midfield an excellent one," Bradley said. "He is the type of player that will help us right away."

According to Bradley, the Dips started yesterday with a team meeting, followed by a "good, hard scrimmage" and finished by watching films of the Houston game "to try to pick up tips on what we've been doing wrong.