Sometimes tennis makes you crazy. Sometimes, hanging around tennis even a little bit, you look at a sunset of flame over the skyline and wonder where it's all going to end. At dusk the other day, the sky was a sea of fire behind the Empire State Building, the red clouds a Dali touch behind the graceful shimmering lights of the Chrysler Building. Was E.T. about to return for the men's final of the U.S. Open?

Of all our sports, tennis is the most bizarre. Not in its athletic demands. Only the purest of athletes succeeds in the little boxes split by a net three feet high. Ted Williams was right when he said hitting a baseball is sport's most difficult chore. Hitting a tennis ball where you want to hit it may be next.

At all levels, tennis is a full examination of a player's conditioning, skill and will. It may be the truest test in that the best player almost always wins. In golf, 50 players can win because of changing conditions of courses and weather. A single bad shot can cost two more. Bring the 100 best tennis players together, though, and only three or four can win because in a five-set match there may be 750 points played--and the longer a contest goes, the more it favors the better player.

If conflict is the heart of literature, surprise is the lifeblood of sport. Let's hear it for the underdog. In tennis, the underdog is under forever. Golf produces an Open champion named Andy North. The 49ers win a Super Bowl, the Bullets win the NBA, the Mets win a World Series. When's the last time Cinderella won a big tennis tournament? Only the favorites win in tennis, which is bor-ing to the max.

Chris Evert Lloyd admits it. "It's bad for a player to dominate women's tennis, I guess," she said begrudgingly. "It makes it more interesting for the fans and the press when three or four players are competing for the top, like in the men. It's great for Martina that she's playing so well, but to have more people contending, that does makes it more interesting."

It is as a business, as an entertainment enterprise, where tennis leaves you wanting to chew up a racket.

"The state of tennis?" said a pretty woman from south of Nashville, Tenn., who lowered her sunglasses for a better look at the sort of fellow who would ask such a question even as 15,000 folks took a workday afternoon off to watch the world's two most boring matches--Navratilova pressing Shriver between the pages of her bankbook, and Evert anesthetizing Durie with ground strokes more efficient than Xylocain.

"Tennis is good," the Tennessean said.

She adjusted her straw hat with the red ribbon.

"I have taken two weeks off to be here. And right before that, honey, we retopped our tennis court at home."

Well, shut mah mouth.

With a purse of $2,001,000 this fortnight, the U.S. Open seems healthy enough. With loyal customers such as the plantation mistress up from the South, the game is doing well everywhere. Even the pro tennis administrators, wakened from the dead, have snapped to with the realization that they must police their sport if they want anyone to believe it is an athletic contest and not a Supertramp concert.

The year's suspension of Guillermo Vilas for accepting appearance money is, no doubt, a warning shot across the bow of the other big names. The suspension is hypocritical in that tennis encourages its players to make every commercial tie-in possible. When Mats Wilander was on center court the other day, his tennis shirt carried four advertisements for automobiles and clothing.

Yet the tennis lawmen then chose to punish Vilas, only one of a hundred who have taken appearance money, for pursuing commerce to its logical end. If a tournament sells $100,000 in tickets solely because of Vilas, why shouldn't he get part of that loot? There are lots of reasons dealing with the sport's long-term health. But these are short-term guys, passing through, their hand out for the biggest buck.

Besides which, the suspension is necessary if tennis cares about being a sport.

Certainly, the Grand Slam tournaments are inviolate. Winning the French, Australian, Wimbledon or the U.S. Open makes a player's commerical success. So these are real sports events. There is no appearance money distorting the incentive. There is no prearranged splitting of prize money should buddies reach the final together.

But what about Barcelona, Memphis and Washington? Who is tanking today to get out of town for a big-bucks exhibition? When we read the results in the paper, which are real tournaments and which are glitzy exhibitions with McEnroe playing top banana to Gerulaitis?

There is no identifiable tennis circuit because the top players have sold themselves to so many interests that the integrity of the contest itself runs a distant second to the stockpiling of dollar bills. With tennis, as Gertrude Stein said of Oakland, there is no there there. Four times a year, for the Grand Slam tournaments, tennis is a sport. The rest of the time, it is a gypsy caravan playing three-card monte with the local yokels.

Imagine where this could lead. All these commercial connections that so distort the game's purpose could lead to--what? Could it lead to, ho ho, the U.S. Open champion getting a $500,000 prize from, say, a lady's girdle and bra company?

You think not? Too ludicrous when the Open's own first-prize money is $120,000? Do you think no self-respecting game would allow a commerical tie-in that overshadows its own prize?

Think again. Martina Navratilova's victory today, giving her three of the Grand Slam championships, earned her a half-million bucks from the elastic tycoons.