The Denver Nuggets were down by three points with four seconds left in a National Basketball Association exhibition game with the Los Angeles Lakers Saturday night. The nuggets controlled the ball out front and the Lakers seemed content to let them eat up the final seconds, because they had what they felt was a safe lead.

then all of a sudden, whoosh.

David Thompson jumped skyward from 25 feet out and launched a successful three-point field goal to tie the score.

The panic-stricken Lakers called a timeout, but they didn't have any left and were assessed a technical foul. The Nuggets made the technical shot and won the game.

Welcome to the wild and wacky world of the three-point field goal, the biggest change in the NBA since the merger of 1976. It will make all sorts of weird happenings at the end of quarters and games possible this season, and the NBA is hoping it will add a little spice to its life.

"It's a gimmick, but you've got to take advantage of it because other people sure will," said Bullet Coach Dick Motta.

"It'll open things up just a bit for the guys who are really good at it. we'll have two philosophies. There may be times we just come down the floor and it's there, or we might have a set play to get into it. The times i have in mind are like at the end of a quarter. You don't convert on those shots very often anyway, so why not try the three-pointers then?

"And then when the games are close, it can bail you out. There is certainly some strategy to be made with it and it'll prove to be interesting, but i don't think the league will attract 10,000 more fans a week because of it."

In 82 exhibition games this preseason, the 22 NBA teams made 69 of 264 three-point field goal attempts, 26.1 percent.

The player who tried the most, Stan Pietkiewicz of San Diego, made four of 13 shots.

The bullets made two of five, but Motta didn't have any special plays put in for it. he will by the time the regular season opens Friday, he said.

In eight exhibition games, Kevin Grevey made one of two, Charles Johnson one of one and Roger Phegley and Phil Chenier each missed his only shot at a three-pointer.

The three-point field goal was a staple of the American Basketball Association and it was such former coaches of that league as Kevin Loughery of New Jersey and Bob Leonard of indiana who helped influence the NBA to adopt it for this season.

THE NBA clubs have painted three-point lines on the floors around each basket. The line is three feet in bounds on the sidelines, reaching almost to the free throw line extended, and then arches to 23 feet, 9 inches away from the basket out front. That means a 22-foot shot from the corner or side is a three-point goal.

One of the officials will hold up one hand if a shot is a legal three-point attempt and he will raise the other hand, like a football official signaling a touchdown, if the attempt is good.

A shot will be deemed a three-point attempt if the shooter releases the ball while his feet are behind the three-point line. His momentum may carry him over the line without penalty.

The adoption of the three-point field goal means there can also be a four-point play now. If the shooter is fouled while attempting a three-point goal and the basket is good, he will get one free throw. if the attempt is not good, he will get only two free throw, as he would on a normal field goal attempt.

The distance is well within range for many NBA players.

Louie Dampier of the New Jersey Nets is the premier three-point field goal shooter of all time.In his nine-year ABA career, he made 794 of 2,217 attempts. While with the Kentucky Colonels in the 1968-69 season, he took a league record 552 such shots. He says 22 feet is a long way.

He added that many NBA players will have to change their techniques if they are going to shoot those long field goals.

But as Bernie Bickerstaff, Bullet assistant coach, said, "fifteen feet is a good shot in this league and 22 feet is only seven feet farther out."

The three-point field goal could turn out to be just as much a headache as a help for some coaches. Getting some players not to shoot it could be a problem.

"There will be some guys who think they can make it every time, so they'll be launching them all night," said Seattle's Fred Brown, one of the league's best long shooters. "I think a lot of teams are going to lose more games than they are going to win because of it."

The best long shooters in the NBA now are probably Brain Winters of Milwaukee, Brown, Lloyd Free of San Diego, Grevey and Ruby Tomjanovich and Rick Barry of Houston.

There are still 14 players on NBA rosters who made 10 or more three-point field goals while in the ABA. Included among them are Dampier, George Mcginnis of Denver, Julius Erving of Philadelphia, George Gervin of San Antonio and Don Buse of Phoenix.

Dampier has the best percentage of those players, having made 35.8 percent of his 2,217 attempts.

"You have to shoot better than 33 percent to make those shots worth it," motta said.

"A three-point play at the right time can really change the complexion of the game. In our last exhibition against the 76ers, Dr. J hit one from the corner and we weren't ready for it. It turned the game around.

"The three-point field goal will definitely make things interesting."