Wes Unseld, the hub of the Bullets' smooth-running basketball machine, will miss at least the start of the team's three-game western road trip this week.

Unseld stayed home yesterday when the Bullets departed for tonight's 9:30 (EST) game at Phoenix. His bruised rib cartilage was examined by Dr. Stanford Lavine and, after talking with Coach Dick Motta, Unseld decided to rest for at least another two days.

The Bullets also have games in Los Angeles Friday and Portland Saturday. Unseld possibly could join them for the Laker contest, although the decision is entirely up to him, according to a team spokesman.

His place in the starting lineup will be taken by Mitch Kupchak, the club's third leading scorer (16.8), despite his reserce role.

"We will go with Mitch and Dave (Corzine) and also give more playing time to Greg Ballard," Motta said. "I told by my wife this morning that it was about time for some injuries to start."

Unseld first hurt the ribs Friday night at Detroit while setting a screen. He finished that game and started Saturday against Boston but pulled himself out in the first quarter.

He played briefly in the second quarter, but sat out the entire second half while Kupchak poured in 22 of his 27 points and the Bullets rallied to beat the Celtics.

"It feels like something is floating around in there," said Unseld, who is known for his pain threshold. "It afftects my breathing and movement. I thought I could have played Saturday night but I wasn't doing all that much out there anyway."

Unseld warmed up at practice yesterday but said he was feeling some discomfort. Motta sent him to Lavine, who devised the special harness.

The injury comes at a time when the Bullets are playing the most consistent basketball in the NBA. They've won four straight and 15 of their last 17 games over the past six weeks. In that span, they have performed both as champs and chumps, but still have managed to pull out victories that even Motta admits, "We would have lost consistently last year."

Their ability to keep winning even when not functioning on all cylinders is perhaps the most marked change in the club since it won the NBA title. The Bullets apparently have been affected by a does of the same champioship elixir that made the Celtics and UCLA so formidable in years past.

"We had some problems winning games last year that were close and on days when our bodies weren't quite right," said Motta. "But it's a different story this year. There is a confidence that seems to be carrying us."

After steamrolling opponents during a marvelous nine-game winning streak, Washington has spent the last eight games trying to overcome a mild case of hesitation, inconsistency and lethargy. Despite the engine knock they've still captured six of those contests.

But Unseld was healthy during all but the last of those games. Although he doesn't score much, his picks, passes and rebounding are vital parts of the Bullet master plan. His absence becomes at a bad time; the team has recent history of poor play on the West Coast, where it lost four straight earlier this season.

"Wes is playing and rebounding about as well as he has in the last three or four years," Motta said. "He's played so well and he does things so quietly. It's hard to replace them."

Kupchak offers the team another dimension. He is not Unseld's equal in rebounding (but he is improving) or setting screens, but he is a much more dangerous offensive threat and he adds to the Bullets' fast-break quckness.

Other than a five-point effort against Detroit, Kupchak has been on a streak. He has scored at least 21 points three times in the last two weeks, making 40 of 64 shots in those games.

"I can't do everything that Wes does," said Kupchak, who is the NBA's highest-scoring reserve, "but in other ways I can do more. I just have to go out and have a good game and not worry about filling any certain role."

The Bullets, whose 22-9 record is No. 1 in the league, have won their last seven road games. . . In their 101-98 victory over Phoenix at Capital Centre, Unseld had 20 rebounds and Kupchak 21 points.Alvan Adams, who missed that game, will play tonight. . . Guard Tom Henderson missed practice yesterday with the flu but is expected to play tonight.