NEW YORK, SEPT. 13 -- Just before 5 p.m. today, the rain that had come down steadily all day at the National Tennis Center stopped and the skies brightened. But it was too late. The U.S. Tennis Association had already sent Ivan Lendl and Mats Wilander home, postponing their U.S. Open final until Monday afternoon.

Lendl and Wilander will play at 2 p.m. (WUSA-TV-9), right after the finals of the women's doubles and the mixed doubles. Both those matches will involve Martina Navratilova, whose route to a possible triple here has been aided considerably by defaults in the last two days.

Saturday evening, shortly after losing the women's final, Steffi Graf defaulted the semifinal she and Gabriela Sabatini were to play against Navratilova and Pam Shriver. Graf had a head cold that did not prevent her from playing singles and would not have prevented her from playing in any other tournament, she said.

That put Navratilova-Shriver in the final against the team of Kathy Jordan and Elizabeth Smylie. Those two denied Navratilova a triple at Wimbledon in 1985, upsetting Navratilova-Shriver in the final, ending the pair's string of eight Grand Slam titles.

Today, shortly after the postponement of play was announced, the mixed doubles team of Raffaella Reggi and Sergio Casal defaulted their semifinal to Navratilova and Emilio Sanchez, Casal saying he was ill.

Both Casal and Sanchez are to play a tournament in Madrid this week. The two are doubles partners and best friends, and the default gave them one less match to play and made life much easier for Navratilova, who might have had to play three matches on Monday.

This morning, with the weather abysmal, tournament referee Gayle Bradshaw had expressed concern about the men not wanting to stay over a day to play mixed doubles. This evening, that fear became reality, an especially disappointing one since the Reggi-Casal team was the defending champion.

The big match, though, is Lendl-Wilander. This is a rematch of the French Open final, won in four sets (match time: 4 hours 23 minutes) by Lendl on a rainy afternoon in Paris.

On this surface, with his 20-match winning streak in this tournament, Lendl is a prohibitive favorite to win his third straight title. Wilander is in the final because he has improved his serve greatly in the last year and because four of the five best hardcourt players in the world -- Lendl, Boris Becker, John McEnroe and Jimmy Connors -- ended up in the top half of the draw. He beat the other member of the quintet, Stefan Edberg, in the semifinals.

"Ever since I won my second French Open {in 1985} I've wanted to improve my record here and at Wimbledon," Wilander said. "Getting through to the final is a step in the right direction for me."

People often forget that Wilander is only 23, because he won his first French Open 5 1/2 years ago at 17. He has four Grand Slam titles, one less than Lendl, but has never made a Wimbledon semifinal and reached the semis here this year for just the second time.

He has worked at becoming more aggressive, even on clay. In Paris this year, he played attacking tennis to rout Yannick Noah in the quarterfinals and Boris Becker in the semifinals, but then reverted to his old backboard style in the final, creating an interminable match. He knows he cannot play that way Monday and hope to beat Lendl.

"I'll have to serve very well to have a chance," he said. "I know I have to come in, even though he'll probably pass me a lot. That's the only way to play him, though."