The undeafeated United State basketball team in the Pan American Games, fresh from its triumph in the world championships in Korea, is a squad of killers, a team without pity.

In the final minute of their 111-73 destruction of Brazil today, U.S. players still were diving for loose ball, fast-breaking relentlessly, substituting at a full sprint and yelling, on defensive switches, "You got help, you got help."

This team hated to see the seconds tick away, hated to stop bludgeoning the Barzilians as it ran the score up and up - towels waving on the bench, feet being stomped at the slightest mistake.

Finally, with 11 seconds left, the four-time All-America guard passed on the fast break to the 1979 College Player of the Year, who, while falling out of bounds, swatted the ball two-handed to the 31.7 point-a-game forward who was cutting for a layup.

"Great pass, Nancy," yelled Carol Balzejowski to Nancy Lieberman as she slapped hands with Ann Meyers.

Now certainly nobody thought we we talking about the US. men's team, did they?

No, the similarity between the United States men's and women's teams here ends with the fact that both are undefeated and both are favored for gold medals in Friday's doubleheader battle of unbeatens - the women meeting Cuba, the men Puerto Rico.

Without question, the Traditional roles in United States basketball have been reversed in these Games. It is the men who ought to be playing in the preliminaries.

The only basketball teams worth watching are those with what players call "a court personality" - the rest are just trading baskets, ad infinitum.

The erratic men's team has struggled vainly to find a presence. They played Brazil today, too, and won easily, 106-88, thanks to a brilliant 28-2 first-half explosion. But by the closing minutes, they were longfaced and bored, listening to coach what's-his-name chew out one more player.

It is the U.S. women who have a sense of themselves, a plan of attack and an identity that crowds can feel. While the men, like starters Kevin McHale and Ronnie Lester, struggle to win with anonymous guts, the women have made the Pan Am Games their showcase with final scores like 124-69, 83-35, and 92-58.

A consciousness seems to exist that these women may never get to play on a team like this again. For speed, skill, finesse and style - although not height - there may never have been a women's squad to match it.

"Crowds love us, and they should," said Coach Pat Head of Tennessee. "We're intense and incredibly deep at every position. We have to platoon because we have players who are so good that you simply can't insult them by keeping them on the bench.

"Because I'm a coach, I won't say we play run and gun, but we're a team that likes to use its head at the fastest possible pace."

This is a team that arrives in waves, like the old Celtics. For true fans of women's hoops, some of the substitutions seem to fog the vision - like Tara Heiss, the great ex-Maryland playmaker, and Lieberman, the best all-around player in the sport, leaving the game to slap hands with Blazejowski (38.6 points per game as a college senior) and Meyers, the 1976 Olympic star.

"I can't get over how good we are," said the ponytailed Heiss. "It's a thrill for us all to play together at once."

Rather than being a team of stars, the United States w omen - partially because Kris Kirchner (6-foot-4 from Maryland) and Jill Rankin (6-3) are not dominant centers - have blended as a unit. The unselfishness of guards Heiss, Lieberman and Meyers sets the tone that helps natural gunners like Blazejowski and Rosie Walker (26.0 points per game for the Ladyjacks of Stephen F. Austin) keep from constantly pulling the trigger from 20 feet.

The other unifying factor, however, is 7-foot-2 and plays for the Soviet Union - a gal by the name of Siminova. For the United States to win any Moscow Olympic gold in 1980, teamwork must overcome staggering Russian height.

"We don't know how you make women that tall," said 5-10 Lieberman of Old Dominion University, who grew up in Far Rockaway and learned her ball on New York City playgrounds where she never played against anyone but boys.

"People say the Russians are unbeatable, out of reach because they have other players over 6-6," said Lieberman, who brought the AIAW national championship to Norfolk this season.

"Well, except for center, I think we're better at every other position, even if we are smaller.

If we can upset the Russians, it will be one of the greatest historical feats in international sports."

That's a mouthful, but it's an idea that keeps this team fresh - especially some, like Lieberman, who have been playing almost continously for a year since last summer's tour to Eastern Europe.

"We're so tired of basketball right now," laughed Lieberman. "We've been together for four solid months."

The U.S. women actually have won 16 international game in a row since April, capturing the World Championship (boycotted by the Soviet Union) in Seoul, and the Jones Cup in Taiwan.

"Puerto Rico actually seems like a return to civilization," said Kirchner, who studied Spanish at Maryland just for this trip. "People were wonderful to us in the Far East, but you'd be amazed how tired you can get of little people speaking a very strange language."

Their travels have certainly brought the United States team together. "Women's teams tend to be more emotional than men's perhaps," said Kirchner. "It's been a long time since we had a big argument or fight."

In that, as in other matters, they are the antithesis of the American men. Today, after their game, the women headed directly to their cars for a day at the beach. The men, in two weeks, have not taken a single tourist break or excursion. One bus tour was canceled because Coach Bobby Knight was miffed about turnovers.

While the men, limited in talent but under enormous pressure, have had to be drudges, the women have developed some flare - several wearing T-shirts that say "Bubba's Angels," in honor of U.S. heavyweight boxer Bubba Hadley, who has adopted them.

Even the prospect of meeting the fast and physical Cuban team seems to them more an opportunity to show their own poise and power than a worrisome threat.