Taking advantage of the absence of Washington boxers, who had controlled the lower weight divisions in the first two years of this event, New York advanced boxers in five of the seven lower weight classes last night in the semifinals of the third annual Mayor Marion Barry Invitational Amateur Boxing Tournament at Howard University's Burr Gymnasium.

However, because Washington's 178-pound Mike Simon decisioned New York's Clinton Mitchell and Washington's super heavyweight Ronald Brown decisioned Robert Salters of Fort Bragg, N.C., in the final two bouts last night, New York is far from a sure thing for the team championship.

In fact, Miami may end up being the team that determines the champion. Tonight's finals, which start at 7:30, will feature New York's five against Miami's four against Washington's five.

It promises to be interesting -- and confusing.

Each gold medalist will earn five points for his team; each silver medalist will earn three. Miami has two points from two bronze medalists. New York and Washington have one point apiece.

"I've been in this game too long to count on anything," said New York manager Jim Borzell, whose team finished second in this tournament in 1985 and third last year. "I've seen too many guys go into the last night of a tournament and collect just three points apiece. Still, I think we stand a pretty good chance of winning this thing."

Washington's other winners last night were 156-pound Darrin Rivers, 165-pound Melvin Foster and 200-pound Jerry Ballard.

Foster's victory over Norfolk's Tony Bonner was impressive. Bonner, 23, had knocked each of his first two opponents unconscious, hospitalizing both. But Foster forced Bonner to one standing eight-count in the second round and another in the third before the fight was stopped just before the final bell.