When the National Basketball Association playoffs begin Tuesday, the preseason favorites and last year's finalists, the Philadelphia 76ers and the Los Angeles Lakers, still seem to be the top teams despite injuries to key players.

The 76ers, who finished the regular season with a loss at Boston today, assured themselves of the home-court advantage for as long as they are in the playoffs. They finished 65-17, the best in the league, despite playing the last four games without center Moses Malone, who has tendinitis in his right knee.

The 76ers' first-round bye should allow Malone to recover before Philadelphia plays the winner of the New York-New Jersey miniseries in a best-of-seven Eastern Conference semifinal series next week.

The Knicks defeated Chicago today, to finish with the fifth-best record in the conference and will play fourth-place New Jersey at the Meadowlands Wednesday.

In the other East bracket, third-place Boston hosts sixth-place Atlanta. Second-place Milwaukee, the Central Division winner, will play the winner of that miniseries in the other Eastern semifinal.

In the Western Conference, the defending champion Lakers will be without standout rookie James Worthy, who has a broken leg. Bob McAdoo, a hero in last year's playoffs, has not played in five weeks and has just come off the injured list after toe surgery. The Lakers have a week to rest before their first game.

The Denver Nuggets defeated the Kansas City Kings, 125-116, tonight, in Denver to gain the sixth and final playoff spot in the West.

Third-place Phoenix begins its first round miniseries against Denver Tuesday and the fourth-place Seattle SuperSonics host fifth-place Portland in the conference beginning Wednesday.

Second-place San Antonio, who many experts feel has the personnel to unseat the Lakers, has a first-round bye and will play the winner of the Phoenix-Denver miniseries in the conference semifinals.