It was their most important game of the season to date and the Washington Bullets played like they didn't care, until it was too late.

As a result, they were beaten by the Cleveland Cavaliers tonight, 118-111, and their playoff hopes were dealt another blow.

The Philadelphia 76ers, of all teams gave the Bullets some hope, though, with a 103-101 victory over the New York Knicks at Madison Square Garden. w

The Bullets now can get into the playoffs for the 12th straight season by winning their last two games. They play the Atlanta Hawks Friday night at Capital Centre and end the season Sunday in Piscataway against the New Jersey Nets.

The Knicks ended their season tonight at 39-43.

The Bullets are 37-43. Victories in their last two games will tie them with the Knicks, but they would get the sixth and final playoff spot in the Eastern Conference through the tie-breaking procedure. The two teams split their season series at 3-3, but the Bullets would have a better record within the conference.

The Bullets still can finish fifth in the conference, but only if they win those last two games and the Houston Rockets, now 39-41, lost their last two. tWashington has won the season series against Houston, 4-2.

And, shouuld that happen, the Rockets would be bumped out of the playoffs by the Knicks, again by tie-breaking rules.

The Rockets were idle tonight, but play host to Detroit Friday and play at Indiana Sunday.

The Bullets were never really in tonight's game until they were trailing by 29 points with 2:18 left in the third quarter.

They scored the last 11 points of that period and the first five of the fourth to cut the lead to 92-79.

They kept closing until they came to within six points on a three-point shot by Larry Wright with 1:09 left, but time ran out on them.

"It's basically impossible to make up 29 points in that short of time," said Kevin Grevey."It's just a matter of hustling and showing some pride after you get down that far."

But with so much on the line, one would expect the Bullets to come out the aggressor.

"I'd think so," said Coach Dick Motta.

Instead, they came out tentative and played most of three quarters as if this were a meaningless exhibition game.

"It looked like they (the Cavaliers) were the ones fighting for the playoffs instead of us," Motta said.

The Cavaliers have won nine of their last 10, but were eliminated from the playoff picture Tuesday.

They came out relaxed and, with the Bullets off their game, moved to a 23-10 lead.

Dave Robisch, who led the Cavaliers with 26 points, had 10 of those first 23 and Mike Mitchell, who set a Cavalier single-season scoring record tonight with 23 points, had seven in that stretch.

The Bullets, behind Wes Unseld's 11 points, had cut the lead to 29-26 by the end of the period, but the second quarter spelled doom for Washington.

The Bullets stood around, both on offense and defense, and the young Cavaliers ran circles around them.

Washington missed seven of its first eight shots and scored only two points the first 2 1/2 minutes of the quarter, while Cleveland scored 13 points, five coming from Bill Willoughby.

Then, with a 44-32 lead, the Cavaliers scored 12 straight points, Willoughby and Mitchell getting four each.

Grevey hit one of his three three-point shots of the night to give the Bullets a little spark and by halftime they were down only 57-41.

But Elvin Hayes made only one of seven shots and had four fouls in that half and Greg Ballard was three for 12 shooting.

The only thing that had kept the Bullets even this close was Unseld's seven-for-seven shooting and his eight rebounds. He led Bullet scorers for the night with 22 points.

Little changed after intermission as Robisch kept hitting those 15-foot, left-handed jumpers, Mitchell continued scoring and Foots Walker and Randy Smith zipped around for uncontested layups.

Wright's speed made a difference down the stretch and he scored 10 of his 16 points in the fourth quarter before fouling out.

"It was just one of those games," said Hayes. "Greg and I have played a lot of minutes lately and it caught up to us tonight. We just didn't have it."

And there was no one but Unseld to pick up the slack.

The alleged "big scorer" off the bench, John Williamson, played five minutes, missed all three shots and looked bad doing it.

"We just couldn't get involved," Unseld said. "Nothing worked."

"We seemed loose and ready to play, but this team is difficult to read," Motta said. "You never know what they're thinking or what they're going to do."