NEW YORK, SEPT. 11 -- One year ago, Steffi Graf almost stole the U.S. Open from Martina Navratilova. In the process, she won the hearts of this city's tennis fans. Today, Lori McNeil played Graf's role. She didn't win the tournament, but she certainly passed the audition.

For 100 minutes on a cool, breezy evening, Graf and McNeil turned the stadium court of the National Tennis Center into Heartbreak Hotel. They took the crowd on a roller coaster ride full of brilliant, tenacious, gripping tennis. When it was over, Graf had proven why she is already a champion, coming from behind to beat McNeil, 4-6, 6-2, 6-4, to reach her first U.S. Open final.

Waiting for her there will be The Champion -- regardless of what the current rankings say -- Navratilova. In this afternoon's first semifinal, Navratilova dispatched Helena Sukova, 6-2, 6-2, in 53 minutes.

"I knew I was going to be asked about whether it was disappointing to win so easily in an Open semifinal," Navratilova said. "The answer is no. After the year I've had, I'll take any easy match I can get."

It is a measure of Navratilova's remarkable ability that this is considered an off year for her. She has now made all four Grand Slam finals in 1987 and 11 straight, dating to 1984. Go one step further and you will find that she has now reached 17 of the last 18 Grand Slam finals dating to the 1983 French Open, winning 11 of them.

She and Graf are now the major rivalry in women's tennis. This will be their third straight Slam final. Graf won the French; Navratilova, Wimbledon. This match should decide who the No. 1 player in the world is right now, especially since the DecoTurf II hard court is the fairest surface in tennis.

McNeil almost denied Graf her shot at breaking the tie. Graf played with a head cold and a slight fever, but it didn't seem to affect her. She played brilliant tennis when she had to and still, McNeil was one easy forehand volley from control of the final set.

If ever a player was entitled to be nervous, it was McNeil. She had not played in the stadium before, had not so much as practiced on the court before this morning. This was her first major semifinal and she was facing a player with a 61-1 record in 1987.

Yet McNeil came out flying. She knew exactly what she wanted to do with Graf and, right from the start, she did it. "I had to keep the pressure on her," McNeil said. "That's the only way to play her. I didn't want her to rush me. I wanted to go at my own pace."

Graf did not appear prepared for the pumped-up play of McNeil, the first black woman to advance to the semifinals of this tournament since Althea Gibson won her second straight U.S. Open in 1958. "I was surprised she played so well in the beginning," Graf said. "I really didn't think she could keep it up for the whole match."

McNeil broke to lead, 3-2, in the first set when Graf twice was long with forehand passing shots. McNeil was doing to Graf exactly what she did to Chris Evert in the quarterfinals: making her pass on almost every shot. At times, Graf did just that, zapping her forehand to the corners.

"I knew that was going to happen," McNeil said. "It didn't bother me. She hit some great shots, some really great shots. That's what won her the match."

McNeil didn't blink once she had the lead in the opening set. She held her serve at love to lead, 4-2. By this time the crowdmen's was exhorting McNeil. Even though McNeil is 23, five years older than Graf, she was the underdog and she is an American. These days, young Americans who can play are so rare that they inspire some chauvinism.

McNeil is not a player who shows a lot of emotion, but she was feeding off the crowd. Because she is capable of spectacular shotmaking, she came up with some superb gets and winners. She also missed some easy shots. Everyone rode with her, cheering the gets, groaning at the errors.

She served out the first set, ending it with a second-serve ace down the middle. That earned her a standing ovation. Graf, however, is not one to quake in the face of winners or raucous fans. "I knew she had to make some errors," she said. "I had to be patient and keep hitting and wait for the mistakes. Fortunately, in the second set, they began to come."

Not in bunches, but just enough, especially when added to the winners that began flying off of Graf's racket. She broke McNeil in the second game of the second set with two stunning forehands down the line and ran out the set from there.

At that point there was every reason to believe that McNeil's day was done. She had played her one great set, thrown her best right and it had not been enough. But McNeil has proved this week that she is not that kind of player.

She began the third set by putting Graf in a 0-40 hole. Graf came back to deuce and they dueled through five more. Graf saved five break points, McNeil two game points. Finally, on the sixth break point, McNeil came in behind a backhand return and crushed a forehand volley to go up, 1-0.

Helped by a McNeil double-fault, Graf broke right back, nailing another of her trademark forehands at 30-40. From there, she ran out to a 3-1 lead, and once again, McNeil looked done. She wasn't.

McNeil broke back to 3-2, then held for 3-all. Suddenly she had put Graf in a position few people have been able to in the last two years: in a tight third set against a decided underdog. When McNeil got to break point in the next game, Graf was most definitely in a corner.

McNeil got a second serve, hit a good, deep backhand return and came in. Graf ran it down and floated a forehand back. McNeil lined it up, a classic sitter forehand volley. She swung the racket back -- and missed, the ball cracking the net tape. For a moment she stood stock-still as if she wanted to join the huge groan that had gone up.

"I just took my eye off it," she said softly. "I'll never forget that one."

That was McNeil's moment. Graf held from there with a magic crosscourt forehand so sharply angled McNeil would have needed a fifth-row seat to play the ball.

It was 4-5, and McNeil was spent. Graf won the 10th game on a blasted forehand.

"I was just glad to win," Graf said. "She played so well, I never felt comfortable. I was not calm enough, I think, because I wanted to play Martina in the final."

Now, she will get that chance.