Serena Williams has to wait for U.S. Open semifinal

NEW YORK — Serena Williams — and the rest of the world — will have to wait another day to get one step closer to the calendar Grand Slam.

With rain forecast throughout the day, the U.S. Open postponed Thursday's evening session, set to feature both women’s semifinal matches, including world No. 1 Williams.

Instead, Williams will play her semifinal match against Roberta Vinci, the world No. 43, on Friday at 11 a.m. Simona Halep, the No. 2 seed, and Flavia Pennetta will also play Friday afternoon.

The originally scheduled men’s semifinal session, scheduled for Friday afternoon, has been pushed back to early evening, beginning at 5 p.m.

In the men’s semifinals, top seed and world No. 1 Novak Djokovic takes on Marin Cilic while Roger Federer, the No. 2 seed, meets countryman Stan Wawrinka.

Williams, champion here each of the last three years, will be forced to think overnight of the challenge that awaits her: She’s two matches from completing tennis’ Grand Slam – winning all four majors in one year – which hasn’t been done in tennis since Steffi Graf in 1988.

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Persistent and heavy rainfall is expected in the Queens borough of New York on Thursday evening, starting around 6 p.m. and lasting through the night. Friday calls for mostly cloudy – yet dry – conditions.

The USTA is trying to avoid another final-weekend headache at the U.S. Open. For five years – between 2008 and 2012 – rain near the end of the tournament meant pushing the men’s final to a Monday finish. In 2013 and 2014 the tournament schedule called for a men’s Monday final, regardless.

Fans holding tickets for Thursday night’s women’s semifinal session, Session 21, will be allowed in for the Friday afternoon session matches. Ticketholders for Friday afternoon will now be let in Friday evening.

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