The Portland Trail Blazers have misplaced the key to winning NBA playoff games, but they're positive it will return today at home in the final game of a best-of-five series against the Seattle SuperSonics.

If not, the Sonics, a lowly eighth-seed matched against the team with the best regular-season record, will have pulled off arguably the most stunning upset in NBA playoff history.No team with the best regular-season record has ever lost in the first round (three- or five-game series) of the playoffs, though the 1968-69 Baltimore Bullets opened the playoffs in the semifinals and lost 4-0 to the New York Knicks.

The Sonics, 41-41 this season, already have become the first eighth-seed to win two games and would become only the fourth team to win a five-game series after losing the first two.

"The key," says Portland Coach Rick Adelman, "is for us to remember how good a team we've been. Sometimes losing two like this, all you can think of are those two losses. We just have to play like we're capable of playing."

The Blazers, 69-13 this season and a loser to Detroit in last year's NBA finals, are banking on their playoff experience to thwart the charging Sonics.

"It's a one-game series now at our place," said guard Terry Porter. "With the veterans we have on this team, we'll bounce back and play our game. The real Blazers will show up Saturday."

The Blazers have had a difficult time all year with the Sonics, though they managed to pull out victories in each of the first six games between the teams. But the Blazers stumbled while the Sonics made the big shots and plays in Games 3 and 4 in Seattle.

For example, the Blazers lost a 5-point lead in the final three minutes to lose 102-99 Tuesday night; Thursday they made only 3 of 10 free throws (20 of 39 for the game) and committed six turnovers in the last six minutes of the fourth quarter.

Equally uncharacteristically, the Sonics, who have struggled with their offense this season, scored 17 points and made four steals inside the final five minutes of Game 4.

"We made all the big plays, did all the right things,"said Seattle's Eddie Johnson, who scored 34 points Thursday. "Hopefully, we're now at the point where we know we can beat them, even on their homecourt. We'll need that kind of attitude to win Saturday."

The keys for the Sonics are Benoit Benjamin and a defense that has stopped the Blazers from going on any sustained scoring runs during the last two games.

Benjamin scored only 20 points in the first two games, but he exploded when his teammates finally started getting the ball to him down low in the games in Seattle. He has 40 points, 14 rebounds and 8 blocked shots in the last two games.

"When my teammates get me the ball on offense I just feel more a part of the game," said the 7-foot center.