FLUSHING, New York (Ticker) -- Forget the No. 1 player in the world. Forget the defending champion. If and when the rain lets up today, all eyes will be on sisters Venus and Serena Williams as they try to make the U.S. Open women's final a family affair.

Serena Williams, the seventh seed, is scheduled to play defending champion, fellow American and second seed Lindsay Davenport in the first semifinal match today. Third seed Venus Williams, who at age 19 is two years older than Serena, continues her rivalry with Switzerland's Martina Hingis, the top seed and the top player in the world, in the second semifinal.

Heavy rain has delayed the start of the men's doubles final -- the first match on today's program at Arthur Ashe Stadium -- and as much as two inches of rain is expected to fall in the New York area throughout the day. Tournament officials have announced that play will begin 30 minutes after the rain stops and moved the men's doubles final to Louis Armstrong Stadium.

The Williams sisters will be trying to fulfill their father's pre-tournament prediction and set up the first Grand Slam final between sisters since Maud Watson defeated Lilian Watson in the 1894 Wimbledon final. Richard Williams, who serves as coach for both of his daughters, guaranteed both Venus and Serena would reach the final after learning they were in different halves of the draw.

But to make it happen, the Williams sisters will have to get by the top two players in the world and the last two U.S. Open champions.

Hingis defeated Venus Williams in the 1997 U.S. Open final and owns a 7-3 advantage in the head-to-head series. The 19-year-old Hingis has won three of the last four meetings, including a 6-4, 6-0 victory in the final of last month's event in San Diego.

Hingis, who is shooting for her sixth Grand Slam singles title, has been nearly unstoppable during the summer hardcourt season. In addition to San Diego, she won in Toronto and owns a 20-1 record, with the only loss coming to Serena Williams in the Manhattan Beach final.

Hingis, the only semifinalist not to lose a set at this year's U.S. Open, easily dispatched unseeded Anke Huber of Germany, 6-2, 6-0, in the quarterfinals.

Venus Williams has won five titles this year, including the U.S. Open tuneup in New Haven, and also made the finals in San Diego and Stanford this summer. She ousted 12th seed Barbara Schett of Austria, 6-4, 6-3, in the quarterfinals.

"I really don't think, if Venus is playing on, I don't think there's anyone out there that can beat her," Serena Williams said of her sister's chances against Hingis. "I think Venus just needs to go out there and play her game."

Davenport captured her first Grand Slam title here last year by ousting Venus Williams in the semifinals and defeating Hingis in the final. She earned her second major championship earlier this summer at Wimbledon and has held the No. 1 ranking for a total of 22 weeks in her career.

Dominant through the first four rounds of this year's tournament, the 23-year-old Davenport ran into trouble in her quarterfinal match with fifth seed Mary Pierce of France. After winning the first set, she dropped the second and survived two match points against her before rallying for a 6-2, 3-6, 7-5 victory.

Serena Williams, who has won three titles this year, will be appearing in her first Grand Slam semifinal. She advanced with a 4-6, 6-3, 6-2 victory over fourth seed and fellow American Monica Seles in the quarterfinals.

The younger Williams holds a 2-1 lifetime edge over Davenport. Davenport won the first meeting two years ago indoors in Chicago, but Williams has won the last two, each on hard courts.

"I think Serena will go out there and start fighting," Venus Williams said. "That's all that matters. As long as she wants to win, is going to put forth the effort, that's good.'

When their work in singles is done, Venus and Serena Williams will face Pierce and Schett in a women's doubles semifinal. The Williams sisters are seeded fifth, and Pierce and Schett are the 12th-seeded team. The winner will face the unseeded duo of American Chanda Rubin and Sandrine Testud of France in Sunday's final.

The men's doubles final will feature the top-seeded Indian duo of Leander Paes and Mahesh Bhupathi and the tandem of American Alex O'Brien and Canadian Sebastien Lareau, the 11th seeds.

Paes and Bhupathi will be gunning for their third Grand Slam doubles title of 1999. After losing in the finals at the Australian Open, they captured titles at the French Open and Wimbledon. Bhupathi added another crown to his collection Thursday when he teamed with Ai Sugiyama of Japan to win the U.S. Open mixed doubles title.

O'Brien and Lareau are appearing in their third Grand Slam doubles final. They lost in the finals at the Australian Open in both 1996 and 1997. In addition, O'Brien advanced to the doubles final at the 1995 U.S. Open with Sandon Stolle.