Charles Johnson, used sparingly in the first two games, came off the bench and scored 10 fourth-quarter points tonight to lead the Washington Bullets to their first victory in three preseason starts, 97-94, over the Detroit Pistons.

The Bullets trailed going into the fourth period, 73-65, but scored the quarter's first eight points. Johnson got the last four to tie the score, 73-73.

The lead seesawed until the final 1:05 when the Bullets went ahead to stay, 94-92, on a layup by another reserve guard, Gus Bailey. Dave Corzine set up the bucket on a pass.

Greg Ballard made a free throw 10 seconds later and Johnson rebounded Bob Lanier's shot, turning it into a fast-break basket for Corzine to seal the victory.

The Bullets will conclude this three-game exhibition, swing Sunday night against the Cleveland Cavaliers in Wheeling, W.Va.

"I think we were a little more intense than we have been," Bullet Coach Dick Motta said. "Of course we were trying to win, but we still followed our game plan."

Roger Phegley led the Bullets with 15 points, his best outing this preseason.

The 6-foot-7 guard, competing with Kevin Grevey for a starting spot, shot 0-2 and committed three fouls in the first five minutes of the game and sat out the rest of the half.

He came out firing after intermission, scoring all of his points in the third quarter, including 10 straight points to open the period.

"I just went ahead and did some things and had some success with them," Phegley said. "It seemed that in the first half whenever I went to the basket they called an offensive foul on me.

"Tonight's game was something I needed because before I wasn't taking advantage of the opportunities that have been there."

Phegley had made only six of 17 shots going into the game and after missing his first two tonight, made five of his last eight.

Bailey, who turned in his second straight strong performance, had 10 points and six assists in 18 minutes tonight.

John Long led Detroit with 20 points and Bob Lanier added 17.