Maryland's optimistic preparations for the Atlantic Coast Conference basketball tournament, which included yet another round of congratulations for all-America Len Bias, were interrupted yesterday by a piece of bad news: J.R. Reid, regarded as the nation's most highly prized recruit, announced his intention to play basketball for nemesis North Carolina next year.

Reid's early decision came as an unpleasant surprise for Coach Lefty Driesell, who had been happily preoccupied in getting ready for Maryland's meeting with the fourth-ranked Tar Heels in the first round of the ACC tournament Friday at Greensboro Coliseum.

Driesell had considered Maryland to be a strong contender for the 6-foot-10, 250-pound forward. The coach learned the news late Monday night from Dick Ponti, Reid's coach at Kempsville High School in Virginia Beach.

"I was shocked," Driesell said. "I was disappointed, naturally. Players like J.R. don't come along often. But they usually end up going to North Carolina. That part's no big shock."

Reid's decision marred an otherwise pleasant day for the Terrapins, which began with the news that Bias had been named a unanimous choice as the Atlantic Coast Conference's player of the year and was voted a first-team all-America by the U.S. Basketball Writers Association.

Bias is scoring an average of 21.3 points, the highest in the ACC since 1976, when Kenny Carr averaged 26.6, and he should break Maryland's all-time scoring record when the Terrapins meet North Carolina. He needs only six points to tie Albert King's record of 2,058.

Bias conducted a television interview, but otherwise refused to comment on his awards or the tournament, saying, "I don't talk before games. Television is different."

He was joined on the first-team all-America squad by Duke guard Johnny Dawkins, who is from the District of Columbia; Kentucky's Kenny Walker; St. John's Walter Berry, and North Carolina's Brad Daugherty. Two area players were named to the second team: Navy center David Robinson and Virginia Tech guard Dell Curry.

Reid's decision adds an interesting sidelight to Maryland's meeting with the Tar Heels and perhaps is further motive for the upset-minded Terrapins. Reid had narrowed his decison to five finalists: Maryland, North Carolina, Virginia, Iowa and UCLA. But he had said previously that he would wait until April to make his choice.

"I just hope he plays poorly against us next year," Driesell said. "I had hoped he would take his time so we might get another chance to talk to him. The funny thing is, his coach told me he had on a Maryland shirt last night, then all of a sudden he decides he's going to North Carolina."

A first-team high school all-America, Reid has averaged 24.6 points and 14 rebounds this season and is hitting 67 percent from the field. In announcing his decision, Reid said he narrowed his choices to North Carolina and Virginia and settled on the Tar Heels after two days of lengthy discussion with his father, Herman.

"There's no sense in prolonging it," Herman Reid said. "I wanted him to get it over with . . . He's been fair with everyone. They were all great programs, but J.R. can't go to all of them. It's like having five girlfriends and you marry one. The other four are going to be disappointed."

"They've got a great program, a lot of great players and their communication program is one of the tops in country," the younger Reid said.

Driesell was otherwise cheerful as he reviewed Maryland's prospects in the tournament at a weekly news conference. The Terrapins are regarded as something of a comer in light of their radically improved play lately; four players averaged in double figures in the last four games, and they have one upset of the Tar Heels already, a 77-72 victory Feb. 20.

Although Maryland is certainly considered an underdog, it goes into the tournament playing its best basketball of the season. The Terrapins have won six of their last eight games. North Carolina, meanwhile, finished its schedule by losing three of its last four.

More important, Maryland is healthy, and North Carolina has two players with major injuries. Guard-forward Steve Hale practiced yesterday for just the second time since suffering a partially collapsed lung against the Terrapins, and reserve center Warren Martin has yet to work out since suffering a sprained foot in the same game.

Ultimately, Maryland may simply have more at stake. The Terrapins are still trying to vindicate themselves after a ragged regular season in which they played what the NCAA has designated the toughest schedule in the country, losing their first six conference games, and although they are reasonably sure of an NCAA tournament bid, a first-round victory would make them virtually certain of one.

Driesell pointed out that Carolina, No. 1 Duke and No. 5 Georgia Tech, which would be Maryland's next opponent of it beats the Tar Heels, are already assured of NCAA berths and that as many as six ACC teams could receive bids. He also said that, as a result, there is not as much pressure on younger coaches such as Duke's Mike Krzyzewski and Georgia Tech's Bobby Cremins as in the days when only the winner received an NCAA invitation.

"I'd like to see these Duke and Georgia Tech coaches if only one team could get into the NCAAs," Driesell said. "They'd be tight as a drum. The young guys have it easy. There's a big difference in the attitude now. They know they're going to be okay. You used to have to win the thing. Brother, that was pressure."