America loves brashness, the more brazen the better.

James Dean proved the point with his hot cars and cool talk before Muhammed Ali unleashed his Louisville Lip upon the boxing world. Then Jimmy Connors thrashed his way into the hearts of thousands at courtside with a two-fisted backhand and a vulgar mouth. Americans followed his saucy service to the courts.

Now there are signs that tennis, along with Conners, is cooling off. Racquetball and squash are hotter than ever, the sports of the '80s.

The national weathervane, A.C. Nielson Market Research, says 20.1 million tennis players were on the courts in 1973, when Conners was No. 1.

By the following year, the number reached 33.9 million. Nielson's Bob Halstenrud says "Tennis was the stellar growth sport of the '70s."

Now Connors is no longer the best nor the second-best. Those slots are occupied by McEnroe and Borg (or Borg and McEnroe). And tennis is no longer the latest thing in latest things.

A recent Washington Post survey of recreational habits found that among area players 26 percent said they playing the same amount, 30 per cent play more and 44 per cent play less than in 1978.

The dropoff is occurring although the survey suggests tennis has become a more egalitarian activity. It has moved away from the traditional white, country-club setting. And, the survey concludes, income does not affect what was once a rich man's game. A difference of less than 5 percent exists in the playing habits of those earning under $8,000 annually and those making more than $50,000 a year.

At one of the city's better addresses, 1600 Pennsylvania Avenue, a spokesman says, "There aren't many people around here with time to play." And although the White House isn't where you're likely to hear it, another factor is the economy.

At Arthur Ashe and Friends, the area's largest retail tennis outlet, sales are 10 percent below projected revenues. "Add in inflation and the numbers are worse," said general manager Van MacNair.

One store manager noted that in the last year the cost of a popular tennis shoe, the Rod Laver model manufactured by Adidas, increased in price from $23 to $38.

Charles Kronke says tennis might be over. Kronke, the general manager of the concessionaire for the National Capital Parks program, said Washington's public courts are growing less crowded.

Recreational specialists in Arlington, Prince George's and Montgomery counties say fewer players are taking to their courts.

In Arlington, which has a high proportion of sporty young adults, Connie McAdam, a county park official, says: "My staff is telling me that the courts are receiving less play. Its slight, but they say there's somewhat of a decline."

On a recent cloudless Saturday morning at the intersection of South 26th and South Lang Streets, only a gentle breeze was playing on the courts.

"It's easier to get a court," said Norma Nesbit, an Arlington resident who plays several times a week.

At the private Fort Meyer courts, a sign on the tennis clubhouse door warns that the courts will close earlier on Friday night "due to a lack of interest."

In Prince George's County, recreation specialist say there has been a 10 to 20 percent falloff in play on county courts.

Despite these suggestions that tennis may be becoming passe, it's far from dead.

In Montgomery County, park official Jim Thomas says the demand for court time "isn't quite what it used to be. It's still high, but it has peaked out nationally." Thomas calls tennis a "deeply entrenched sport." At the same time, he says handball, soccer and paddle tennis are up-and-coming sports.

The Nielson figures tend to agree. Between 1976 and 1979 tennis drew fewer than 2.7 million first-timers -- a considerable slippage compared to the 13 million new fans that flocked to the game from 1973 to 1974, according to a special one-year survey. "The sport has sort of peaked out," says Halstenrud. "Some jumped on the bandwagon and they realized they didn't have the skill to play."

Donnie Chite, another Montgomery official, thinks tennis has merely grown up. She says the county once held 500 tennis classes a year. "Now we have about 150. More people are signing up for tournaments. The sport is definately maturing."

In contrast, local squash courts report time sales are up and racquetball is gaining prominence on the sports scene. In 1976, Nielson found 2.8 million racquetball players, a total that mushroomed to 10.7 million by 1979, a 283 percent increase in three years.

"Racquetball is the in sport of the lat '70s and '80s," says Halstenrud.

Because of its own growing popularity, Nielson will include squash in its triennial survey for the first time in 1982.

A University of Maryland psychiatrist, Dr. William Carpenter, says the big increase in running and aggressive sports like squash is because "one can complete a vigorous workout in much less time."

Carpenter suggests people are looking for condensed activity, some in confined areas of play, that "may be more fit for a pressurized society."

Another psychiatrist, Dr. Michael Sacks at Cornell University, says the general failure of "the institutions, love and family" has induced a new narcissism. "Eminently successful and capable people are saying 'I am No. 1.'

"People are becoming increasingly self-centered with a focus on personal attractiveness, health and physical fitness. That kind of preoccupation with the self is a pathological narcissism that we are seeing increasingly in our practices."

Sacks says "in squash you 'kill' someone or you let yourself be 'killed' and after the game is over it doesn't matter. It's not real, there are no consequences. In love and in work, there are always consequences. In work, if you are murderous you may have terrific consequences to pay, whereas in racquetball you can go out and have a beer with the guy you 'killed.'"