As recently as one month ago, Don Collins had a reputation as a player who was undisciplined, didn't listen to his coaches and sulked. His teammates even nicknamed him "The Devil" because he always had a scowl on his face.

All that has changed lately. The 6-foot-6 second-year guard from Washington State has demonstrated over the last five games that he has considerable talent, and the Bullets are utilizing his skills to the hilt.

The Bullets take on the New Jersey Nets at Meadowlands Arena tonight (WDCA-TV-20 at 7:30 p.m.) in the first game of their first-round, best-of-three National Basketball Association playoff series. And Collins will be going head to head with New Jersey star Ray Williams, who scored 52 points in the Nets' last game.

An injury to Kevin Grevey has meant more playing time for Collins and he has made the most of the opportunity. Grevey basically is a jump shooter who needs the offense to work well to get his shot. Collins plays a wide-open, fast-breaking game and creates most of his own scoring opportunities.

Collins has started the last five games and averaged 20.8 points while shooting 67 percent from the field. He also averaged 4.4 rebounds, three assists and 2.4 steals. He also has been playing decent defense. He limited Atlanta's Eddie Johnson to eight points in the Bullets' 99-96 victory Sunday, which gave them fifth place in the Eastern conference.

And, occasionally, he even smiles.

Grevey still is very limited with an abdominal muscle pull, but Coach Gene Shue said yesterday that even if Grevey was healthy, he'd stick with Collins.

"Of course I'd like to have Kevin," Shue said. "His outside shooting is really important to us, but even if he is ready to play tonight, I'm going with Don. He's really going good and we aren't going to change anything now."

"I proved I'm ready to play and I think finally Coach respects my game and has confidence in me," Collins said. "I learned to listen to him and it is paying off. He (Shue) wants me to do the things I do best--play good pressure defense, get out on the break and get points off the transition game."

Grevey worked out yesterday, but said he feels he is getting worse instead of better. "I want to do whatever I can to help, but it looks like the best I'll be able to do for awhile is just be a spot player," he said. "It doesn't feel good at all."

Grevey said he sustained the injury, which is low on his right side just in front of his hip bone above the groin, "weeks ago and I aggravated it in Chicago a few games ago. I couldn't even lift my leg after that."

With Grevey doubtful, that leaves Garry Witts, a 6-7 rookie, as Collins' backup.

Because Williams is only 6-2 and the other Net guard, Darwin Cook, is 6-3, the Bullets might use John Lucas and Frank Johnson together in the back court.

Shue is not happy with Lucas, however, after the veteran guard showed up for Sunday's game three minutes before tip-off. Shue used him only two minutes against the Hawks and is uncertain how significant a role he will play against the Nets.

The Bullets play more of a gambling defense and running offense when Collins is in the game. When they go to a set offense, Collins usually lines up at a low post. Grevey almost always plays outside.

"Don likes to post up and he gets a lot of easy buckets because he's always looking to drive," said forward Greg Ballard. "It's an upbeat tempo when he's in the game. You have to cater to what the players can do. Kevin is looking for the 15- 18-foot jumper and Don is trying to go all the way. That puts added pressure on the defense."

"I don't think I can shoot as good as Kevin," Collins said. "I want to get as close to the basket as I can."

Collins said he is ready for the challenge. "No one man is going to beat us," he said. "I'll get help on Ray and he has to remember that he is going to be guarding me, too, and I'm going to be out and running."