Frank Johnson converted a three-point play with 42 seconds remaining and Spencer Haywood and Don Collins each added one free throw in the final four seconds and the Bullets beat the Portland Trail Blazers, 100-97, tonight for their third victory in four games of the present six-game road trip.

Johnson made an off-balance jumper as he was fouled by Bob Gross and then converted the free throw for a 98-96 Bullet lead. Billy Ray Bates was fouled by Jeff Ruland with 23 seconds left, but made only one of two free throws, to keep the Bullets one point ahead, 98-97.

The Bullets then played perfect keepaway, passing the ball crisply until the Trail Blazers were forced to foul Garry Witts with four seconds remaining. Witts was away from the ball when fouled, by Kelvin Ransey, and by NBA rules any foul away from the ball in the final two minutes is treated as a technical foul and the offended team retains possession.

Haywood made the technical foul shot for a 99-97 lead and then, after the Bullets inbounded the ball, Collins was fouled by Bates and made one of his two shots for the three-point Bullet lead with two seconds left.

Jim Paxson missed a desperation three-point attempt at the buzzer and the Bullets had held Portland under 100 points for the second time this season. The Trail Blazers have failed to score 100 only seven times all year.

Greg Ballard led the Bullet scorers with 22 points and John Lucas added 14. Johnson scored 11 of his 13 points in the final period. Paxson was high for Portland with 24 and Mychal Thompson had 21.

Johnson missed two straight jumpers, allowing the Trail Blazers to take a 96-95 lead with a minute to play on two baskets by Ransey.

The Bullets were ahead, 80-79, midway through the final quarter when Johnson made two straight 22-foot jump shots to give them an 84-79 lead and they needed every point of that cushion to hold off the Trail Blazers.

Tonight's victory evened the Bullets' record at 25-25 and moved them ahead of New Jersey for the fourth best record in the Eastern Conference.

The Portland defeat was only the Trail Blazers' seventh against 18 victories at Memorial Coliseum.

"We did virtually everything perfect in those final seconds," said Bullet Coach Gene Shue. "If you move the ball quickly enough the defensive team just can't cover the ground. That's why they have the rule about fouling away from the ball. It was a gamble Portland had to take because time was running out on them and we were keeping the ball away from them."

The Bullets, once again, played without guard Kevin Grevey, whose injured right hand hasn't responded to treatments. Grevey's right index finger has been placed in a splint to immobilize it and it is doubtful he will be able to play at all the remainder of this trip. The Bullets play the SuperSonics in Seattle Thursday night and conclude the six-game road trip Saturday in Oakland against the Golden State Warriors.

The Trail Blazers weren't at full strength tonight, either, as Calvin Natt, their second-leading scorer and second-leading rebounder wasn't in uniform because of a sprained right ankle sustained in Portland's 107-91 loss at Indiana Sunday.

Lucas scored six points in the first three minutes and the Bullets opened up a 10-3 lead. But the Trail Blazers then outscored the visitors, 12-2, to go ahead, 15-12. Paxson had eight of the 12 points working against Collins.

That was enough for Shue to summon Witts off the bench for Collins. Witts held Paxson to two points the rest of the quarter and Portland led by three, 27-24, as the period ended.

Gross committed three fouls trying to contain Ballard in the first period and was replaced by former Virginia star Jeff Lamp.

The Bullets shot only 29 percent in the first quarter to 63 percent for the Trail Blazers, but still were in the game because they got off 31 shots in the quarter compared to only 19 by Portland.

The Bullets were down, 33-32, when Shue went back to Collins and the 6-foot-6 guard responded with six straight points to stake the Bullets to a 38-33 lead with 5 1/2 minutes left in the half.

Later in the period, Portland came back with a 10-1 burst, Mike Harper scoring six of the points, to take a 45-43 lead.

Ballard made four free throws in the last 30 seconds and the Bullets led, 49-47, at halftime.