Depending on how hard they feel like playing over the final three games of the regular season, the Bullets can help determine their first playoff opponent.

Following tonight's game in Chicago (8:35, WDCA-TV-20), Washington travels to Atlanta Saturday night and returns for the season, finale Sunday against Houston in Capital Centre. Houston and Atlanta are locked in a struggle with Philadelphia for the third, fourth and fifth positions in the Eastern Conference playoff picture.

If the playoffs began today, the Hawks and Rockets would meet in a best-of-three miniseries, with the winner playing the Bullets in the conference semifinals. Houston would have the miniseries home-court advantage because of a superior record.

But the Hawks, a half-game behind Houston, have a chance to move ahead by taking their final two contests (at Detroit tonight and at home against the Bullets Saturday).

That would put pressure on the Rockets, who would have to win their last three games-home against Cleveland tonight and San Antonio Saturday and at Washington Sunday-to prevent a tie with the Hawks. Otherwise, Atlanta, which captured three of four meetings between the two this season, would have the home-court advantage in the miniseries. The Hawks have won 18 straight in the Omni.

Of course, Philadelphia, riding a five-game winning streak, could lose its final two contests, at Indiana tonight and at home against Denver Sunday. If that happens, and if Houston triumphs in its final three, then the Rockets would be the No. 3 team and would meet New Jersey in one miniseries while Philadelphia and Atlanta would square off in the other, the winner playing Washington.

However, it seems more likely that the 76ers, without injured Doug Collins, who has been declared out for the rest of the season with a stress fracture in his arch, would pay New Jersey in a miniseries, with San Antonio awaiting the victor. That would leave the Bullets in the same bracket with Houston and the pesky Hawks, who no one wants to play in a sevengame series because of their tenacity.

Washington's contest Sunday night against the Rockets could well be Houston's most important in a regular season that has not gone as well as that club had expected. Bullet Coach Dick Motta says his team will not let down.

"We have an obligation to the league to play hard," he said. "It wouldn't be fair to either team if we didn't try to come out and do our best."

Motta's goal of giving his subs additional playing time in the final games will be hindered by the continuing manpower shortage.

Mitch Kupchak's back is acting up again and he decided last night to stay home, receive treatments and see if he could play Sunday. Larry Wright is away, attending a funeral in Louisiana.

Tom Henderson, however, will play after missing seven games with a sprained knee. Motta wants to ease him into the lineup gradually so he can regain his timing for the playoffs.

Kupchak's absence was especially disappointing to the coaches since they already had promised him as many minutes as he wanted over the weekend. But the last time he tried to play when his back hurt, he wound up missing another four contests.

Motta remains concerned about the layoff next week before his team embarks on its playoff trek. The Bullets probably will not practice until Friday-they could could begin the playoffs April 15 or 17 -and he is afraid they will lose their sharpness. But the players say they welcome the rest, which they think will do them more good than early week workouts.

Motta on Elvin Hayes: "He should win the MVP award. No one else in the league deserves it more" . . .The Bullets' 54 victories are the third most in the franchise's history, surpassed only by 60 in 1974-75 and 57 in 1968-69. . .The club has a 20-10 record since Feb. 1, although its top six players have been healthy in only five of those contests.