After 7 1/2 months, 886 regular-season games, four miniseries and four conference semifinals, the National Basketball Association still has four teams eligible for its championship.

In the Eastern semifinals, defending champion Boston again will have to contend with chief rival Philadelphia in a best-of-seven series starting at 1 p.m. today in Boston (WDVM-TV-9).

Out west, the Los Angeles Lakers, idle since completing a four-game sweep of Phoenix a week ago, will have to dust off their running game when San Antonio arrives today to start that best-of-seven series (3:30, WDVM-TV-9).

On the way to last year's title, the Celtics won the last three games of the series with the Sixers by five points, taking a 91-90 victory in the seventh game.

The Celtics have had three days to recover from their physical, five-game series with the Washington Bullets and should be primed for today's opener. The second game will be Wednesday night in Boston, then the series shifts to Philadelphia for afternoon games Saturday and Sunday.

"We only played five games against the Bullets, but it seemed like 10," said M.L. Carr. Even though Carr is the Celtics' best defensive guard, he may not be quick enough to contend with Philadelphia's high-scoring Andrew Toney in Boston's most difficult matchup.

"It (the Bullets series) was a very physical series and I think it was good for us," Carr said.

"It helped us to play those tough games with the Bullets," said Cedric Maxwell, who scored 81 points. "When Frank Johnson made that three-pointer to win the second game, that woke us up. We knew then we'd have to play our best to win, and I think we did."

While the Celtics went through a light workout yesterday, the 76ers were traveling and trying to regroup after stopping the Bucks in Milwaukee, 102-90, Friday night on the strength of a surprising 26-point performance by playmaker Maurice Cheeks.

Last year, when the Celtics breezed past Chicago in four games, they had to wait while Philadelphia survived a seven-game struggle with Milwaukee. The 76ers had one day to travel and prepare, yet they won the first game, in Boston, 105-104.

"I think Philadelphia has a legitimate chance this year," Milwaukee Coach Don Nelson said. "To me, Boston is the best team in basketball, but Philly is playing at a very high level right now."

Except for a fourth-quarter letdown in Game 5 at home (a 110-98 loss), the 76ers--especially Toney, who replaced the injured Lionel Hollins, and Cheeks--played very well in turning back the Bucks, four games to two.

The biggest concern of Coach Billy Cunningham is how well 6-foot-11 center Darryl Dawkins will play. He was Philadelphia's most unpredictable player against Milwaukee, constantly in foul trouble. If that happens against Boston, the 76ers won't be able to match up defensively when both Robert Parish and Kevin McHale are in the game.

The Celtics' biggest problem in last year's series was containing Toney, who came off the bench to lead Philadelphia's scoring with 125 points, getting 26 in the opener and 35 in the second game.

With Nate Archibald guarding Cheeks, either Carr or Chris Ford will have to defend Toney; neither is as quick. Gerald Henderson is available, but Coach Bill Fitch doesn't like to use his two small guards, Archibald and Henderson, together for any extended period.

In the front court, the Celtics have an enormous rebounding advantage and that probably will make the difference in this series. The 76ers were last in the league in offensive rebounding; Boston tied for fourth.

The showcase matchup, of course, is at small forward between Larry Bird and Julius Erving, acknowledged as the game's premier forwards. In last year's series, Bird outscored Erving, 162-123, and outrebounded him, 78-35.

Los Angeles is a solid favorite to eliminate San Antonio, although the Spurs took the season series, 3-2, winning the last two games. The Lakers split two games in Los Angeles and lost two of three in Texas.

George Gervin missed the first game with an injury, but the Spurs won easily, 128-102, as Ron Brewer scored 44 points. In the next four games, Gervin averaged 25 points, seven below his league leading average. The Lakers played very well while sweeping Phoenix, making more than 50 percent of their shots each game and averaging 114 points.

In their surprising 4-1 rout of Seattle, the Spurs' defense was better than usual and was credited with holding the high-scoring Sonics to an average of 104 points a game. The addition of Mike Mitchell has given San Antonio another scorer, but there still appears to be too much pressure on Gervin.

The second game of this series will be played Tuesday night, with Games 3 and 4 set for Friday and Saturday nights in Texas.