Once again the Bullets proved just how fragile their team is, how susceptible they are to injuries, how close they still are to being a last-place team.

When Greg Ballard went out midway through the second quarter with a sprained ankle and Jeff Ruland played only 13 minutes before fouling out, the Bullets couldn't hold off lowly Cleveland and bowed, 100-99, last night before 6,430 at Capital Centre.

The Bullets led through the first half and built a 12-point lead early in the third quarter before folding and suffering the embarrassment of becoming only the fourth team all season to lose to the Cavaliers at home.

After three ties midway through the final period, the Bullets fell behind for good when Reggie Johnson sneaked in for an offensive tip and James Edwards' three-point play gave Cleveland an 87-82 lead with six minutes to play.

The Cavaliers, who lost 11 of 13 games in January, increased their lead to 96-88 with two minutes remaining. Frank Johnson sank a three-point to bring the Bullets within five, then Don Collins (24 points) grabbed an offensive rebound and scored.

Collins stole the ball and drove the length of the floor to score. When he was fouled and made the free throw, the game was tied at 96 with 1:23.

Scott Wedman's short turn-around in the lane put the visitors back in front and, after Collins missed a short turn-around after posting up, the Cavaliers got two straight offensive rebounds and finally scored on a free throw by Johnson with 13 seconds left.

Collins threw an inbounds pass wildly over the base line, giving Cleveland possession again, and Ron Brewer's free throw made it 100-96 before Frank Johnson sank his second three-pointer with seven seconds remaining.

"We were missing two important cogs in our offense with Greg and Jeff out of there," said John Lucas, who contributed 15 points and 10 rebounds. "Those are the two guys we normally go to down the stretch."

Ballard came down with a rebound in the second quarter and his ankle turned in when he landed. There wasn't much swelling afterward, however, and the high-scoring forward said he hoped to play tonight when the Bullets visit Philadelphia (WDCA-20, 7:30).

"This team has to be right to win," Coach Gene Shue said. "We can't afford to have injuries and we have to function properly or we're not going to be successful."

In addition to the loss of Ballard and Ruland, the Bullets were handicaped because Rick Mahorn played the second half with a painful rib after being kneed in the chest by Kenny Carr.

"I wouldn't have played if Jeff didn't get in foul trouble," said Mahorn, who had just two of his eight rebounds after intermission. "It hurts to take a deep breath. I should be all right for Philly, though. We can't afford to have anybody hurt."

One of the walking wounded returned when Johnson came back after a two-game absence. He had 10 points and three assists in 16 minutes, but Shue said that Lucas is playing well and will continue to start at point guard.

"I think I deserve to start," Lucas said, "but it really doesn't make that much difference. We're basically an eight-man team and everyone has to contribute."

Shue cited a defensive breakdown in the third quarter when the Cavaliers scored 32 points as the difference in the game. After making only 33 percent of their shots in the first half (17 of 51), Cleveland connected on 13 of 18 attempts in the third quarter. Reggie Johnson led the rally with eight of his 19 points in the period.

"We knew we wouldn't have Greg and we weren't sure about Ricky," Shue said. "We had held them to 41 points in the first half and I told the team at halftime that we would have to continue to play strong defense in order to win. Then we give up 32 points."

Cleveland made its comeback despite the fact that its leading rebounder, Carr, left early in the third quarter with a sprained left ankle. Wedman replaced him and scored nine points the rest of the way.

Bullets now have lost two straight and with Philadelphia, Los Angeles and Denver coming up, are in danger of starting next week's long road trip on a losing note.