The leading rebounder in the NBA, Moses Malone, and his Houston Rocket teammates play the Washington Bullets tonight at the Capital Centre and the Bullets might be without their best deterrent to Malone's weapons.

Center Wes Unseld is questionable for the game with a sprained left ankle. The 6-foot-7 veteran was injured Tuesday night against Atlanta, and missed the Bullets' 109-94 victory Thursday over the depleted New Jersey Nets.

The Bullets, meanwhile, switched players yesterday, dropping forward David Britton after his 10-day contract expired and adding guard Andre McCarter.

McCarter, a former star at UCLA, was playing for Atlantic City of the Continental League. He was averaging about 18 points and a league-high 10 assists per game. A sixth-round draft pick of the Kansas City Kings in 1976, the 6-3 McCarter has played just one full season in the NBA.

The signing of McCarter to a 10-day contract, however, does not help the Bullets up front. If Unseld can't play, rookie Rick Mahorn again will start, and be backed up by Mitch Kupchak.

Unseld was encouraged about his progress. "It feels better than it did yesterday," he said yesterday, before undergoing one in a series of treatments. "But I don't know. I'm gonna try (to play)."

John Lally, the Bullet trainer, said the ankle had improved "maybe 20 percent" from Thursday, but wanted to avoid any predictions on Unseld's status. "It's a day-to-day thing," Lally said.

Bullet Coach Gene Shue was optimistic about Unseld. "In all probability, he'll play," Shue said. "It looks like it's responding to treatment." Shue chuckled and added, "Maybe I'm just hoping."

With good reason. The Rockets' are built around Malone, a 6-foot-10, five-year veteran who currently leads the league in rebounding (14.1) and is second in scoring (28.1). With Unseld, however, the Bullets have the means of stopping Malone. In six games against Unseld and the Bullets last season, Malone was held to 21 points and 11 rebounds per game, compared to his 26-point and 14.7-rebound averages against the rest of the league.

"The strength of Wes Unseld is matched against the strength of Moses Malone," Shue said. "Moses is a great inside player and a great offensive rebounder. Wes, with his weight (245 pounds), is also a great inside player and rebounder."

Unseld said the key to stopping, or at least dealing with, Malone is to "stay close to him, know where he is at all times."

"He's got a quick step underneath and around the basket," Unseld added. "He stays near the basket. They (the Rockets) take what he does well and they let him do it.He never sets picks, or plays on the high post. They let him move low where he can effectively get the ball and he produces for them."

Starting for Unseld against the Nets, Mahorn scored 14 points with 11 rebounds and four blocked shots. Shue said that although he is confident in Mahorn, he also expects some trouble for the 6-10, 240-pounder from Hampton Institute.

"Rick knows what he's supposed to do. It's just a question of whether he can do it in game conditions," Shue said. "Sometimes it doesn't matter who plays (against Malone). He's a great offensive player. I've seen him dominate some of the best players, so he'll be especially tough on a young player like Rick."

Shue said his goal is to "control Moses. Players have great, average or poor games and we hope he doesn't have a great game and their other players do what they normally do."