The world champion Boston Celtics, beset by early season problems and thought at midseason to be cut of this year's playoffs, have all but clinched a postseason berth with 10 games to play under the NBA's new format that advances the two division winners and the four next-best teams in each conference.

The Celtics host the Washington Bullets tonight at Boston Garden (WTOP-TV-9, 7:30 p.m.). For the Bullets, it will be the first of five games in six days.

The Celtics' woes started before the season when they got into a contract dispute with Paul Silas and ended up trading him to Denver John Havlicek had lost a step. Then Dave Cowens retired. Then Boston found that Sidney Wicks and Curtis Rowe, its prize acquisitions, were not all they were made out to be finally, Charlie Scott broke his arm.

Red Auerbach convinced Cowens to un-retire, Havlicek regained his form, Wicks and Rowe have come around, and Scott is expected back in time for the playoffs.

"We've had a lot of problems to overcome," said Havlicek, "but we never panicked. We've geared ourselves for the playoffs and it looks like we'll be our strongest when the playoffs start. It's a new season then and that's the season that really counts."

The Celtics have floundered around the 500 mark virtually all season. But they have won four in a row and are at 38-34 and closing in on Cleveland and San Antonio, the teams just ahead of them in the Eastern Conference race for home-court advantage in the playoffs.

The Bullets are still hopeful of overtaking Houston and winning the Central Division championship.

After playing the Celtics tonight, the Bullets take on the New York Knicks at Madison Square Garden Saturday (WTOP-TV-9 at 8 p.m.), then return to Capital Centre to face the Knicks again Sunday afternoon.

They then head for San Antonio and a Tuesday game against the Spurs and return here Wednesday for a game against the Atlanta Hawks.

With that many games in such a short period, Bullet coach Dick Motta will rely on his bench. Lately, the Bullet reserves have been outstanding.

Motta went with four reserves, Dave Bing, Mitch Kupchak, Larry Wright and Leonard Gray, in the second quarter against Cleveland Wednesday night after the Bullets had fallen behind by 11 points.

That group stormed the Bullets to a 10-point lead and Washington went on to beat the Cavaliers, 95-90, for its second straight victory.

For the Celtics, coach Tom Heinsohn has been starting Cowens at center, Rowe and Havlicek at the forwards and JoJo White and Fred Saunders as the guards. Wicks is the [WORD ILLEGIBLE] man.

Havlicek plays forward on defense, but moves to the backcourt on offense while Saunders plays defensive guard and offense while Saunders plays defensive guard and offensive forward.

White, the Celtics' leading scorer with a 19.5-point average, has two bone spurs that have slowed him and a bruised chest that is very painful.

Havlicek is the next leading scorer with an 18-point average.