NEW YORK (AP) Serena Williams will have to wait to try to continue her bid for a calendar-year Grand Slam: Her U.S. Open semifinal was postponed because of rain in the forecast.
The top-seeded Williams was supposed to face 43rd-ranked Roberta Vinci of Italy on Thursday night at Flushing Meadows, but nearly four hours before that match would have started, the U.S. Tennis Association - citing a prediction of ''rain throughout the evening'' - pushed back both women's semifinals until Friday.
When the USTA announced the rescheduling, there were doubles and juniors matches in progress.
Williams is trying to become the first tennis player since Steffi Graf in 1988 to earn all four Grand Slam titles in a single season. She won the Australian Open in January, the French Open in June, and Wimbledon in July.
Now the 33-year-old American has won her first five matches at the U.S. Open, and needs two more victories to add that championship to her 2015 collection.
The other women's semifinal moved to Friday from Thursday is No. 2 Simona Halep of Romania against No. 26 Flavia Pennetta of Italy.
It will create a high-profile and packed schedule for Friday, when the men's semifinals already were slotted. In those matches, No. 1 Novak Djokovic meets defending champion Marin Cilic, and No. 2 Roger Federer plays his Swiss Olympic and Davis Cup teammate, No. 5 Stan Wawrinka.
Williams vs. Vinci was supposed to start Thursday night at 7 p.m., followed by the other women's semifinal.
Now the first women's semifinal will begin at 11 a.m. on Friday, when the forecast is much more promising. After that, the other women's match will be held.
The men's semifinals will be played afterward, beginning at 5 p.m., instead of the originally scheduled 3 p.m.
The U.S. Open has a long history of scheduling problems due to weather, including five consecutive men's finals postponed from Sunday to Monday from 2008-12.
As part of a broader, $500 million-plus renovation plan for the tournament site, the U.S. Tennis Association has been constructing a retractable roof atop the main court, Arthur Ashe Stadium, that is planned to be ready for next year's U.S. Open.
For now, a framework of more than 6,500 tons of steel sits atop that stadium, but the work to install the retractable panels will resume after this year's tournament ends.
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