The expensively engraved invitation from the Playtex Co. read: "If Martina Navratilova wins the United States Open, you are cordially invited to attend a press conference and luncheon . . . But please note--if she fails to win the Open there will not be any press conference or luncheon."

No more ifs, ands or buts. Navratilova finally won her first U.S. Open by defeating Chris Evert Lloyd, 6-1, 6-3. For her efforts, she took home $120,000 in prize money and a $500,000 bonus from Playtex for winning three consecutive major women's titles. But in so completely dominating her only rival for women's tennis supremacy, she served notice that she has no peers.

Evert never looked like she had a chance.

The left-handed Navratilova charged the net at every opportunity, daring Evert to pass her. She was particularly effective in the ad court when Evert missed a first serve. Navratilova slid around to midcourt and chipped down-the-line forehand approach shots.

When Evert did try to lob, most were too short, except for a winning game-point loft at 0-2 in the second set. Not that Evert was intimidated. A six-time Open winner, she freely admitted that she "played badly. It was probably the match that I was beaten the worst."

The key ingredients separating Evert and Navratilova were Navratilova's superior athletic talents and Evert's less than ideal determination.

Navratilova is a born athlete, standing 5 feet 10 and a solid 145 pounds. She loves to play tennis; she loves to practice. Tennis is her life. Even Navratilova's entourage is functional, with a former tennis pro, a former all-America basketball player and a nutritionist.

One now has to speculate on Evert's future. Married to a British Davis Cup player, John Lloyd, Evert, 28, is definitely at a crossroads in her career. She may not again find that erstwhile grit to sacrifice whatever it takes to win.

Navratilova is cut from the mold that produced Billie Jean King. No matter how many Opens and Wimbledons she wins, Navratilova will desperately want to win one more. Such is the innate stuff of which great athletes are made.

At 26, Navratilova plans to reign a long time. When asked if there were any women who could beat her now, Evert replied, "Except me, no one."

Navratilova's victory was sandwiched between the men's semifinals. In the first match, Ivan Lendl dashed the hopes of 19-year-old Jimmy Arias by winning in straight sets, 6-2, 7-6, 6-1.

Arias, seeded ninth, never imagined he'd reach the round of four. But his cliffhanger of a quarterfinal five-set victory over fourth-seeded Yannick Noah of France put him there.

Lendl had other plans today. As Navratilova had never won the U.S. Open before today, Lendl has never won a Grand Slam (Wimbledon, U.S. Open, French Open, Australian Open) title.

Lendl went about his task methodically, physically dominating his 5-foot-9, 150-pound opponent. After his victory, he said, "I'm playing very well; what more can you ask for?"

Lendl is very much the male pro tennis player of the future: 6 feet 2, 175-185 pounds, very athletic, well-coached, semiwestern forehand grip, topspin on both ground strokes off a midsize racket. With prize money levels increasing, tennis is beginning to attract superior athletes.

But as much as Lendl wants to win his first Open today, his opponent, Jimmy Connors, may want to win his fifth Open title even more.

Connors limped his way to victory over 16th-seeded Bill Scanlon. His 6-2, 6-3, 6-2 victory was never in doubt. If anything could stand in the way of a repeat of Connors' 1982 Open victory, it may be a toe injury that became visibly apparent toward the end of the third set. In a moment of rage, he accidentally hit his little right toe with his steel racket. Still, he should be ready for today's final.

Scanlon was a picture of utter frustration. Whatever he tried to do, Connors did better. His game plan, worked out by his coach, Warren Jacques, was to move Connors around and get to the net to end the point.

Scanlon hugged the base line in the back court and hit most ground strokes as half-volleys. Eventually, one of his returns fell short enough for Connors to take advantage.

Connors led from the start, breaking Scanlon's first service game. His well-disguised left-handed, two-fisted backhand continually left Scanlon off balance. At 2-1 in the third set, Connors was down, 15-40, only to win four straight points because of four straight unforced errors by Scanlon.