Summary Rain forecast raised concerns of a possible postponement for two night women's semi-final matches
NEW YORK (AFP) - Two triumphs from completing a calendar Grand Slam, top-ranked defending champion Serena Williams might be confronted by an opponent even she cannot defeat -- rain.
Showers delayed doubles and juniors matches Thursday at the US Open and more rain in the evening forecast raised concerns of a possible postponement for two night women s semi-final matches scheduled at Arthur Ashe Stadium.
Williams was set to play Italy s 43-ranked Roberta Vinci in the first semi-final with Romania s second-ranked Simona Halep facing Italian 26th seed Flavia Pennetta in the other. The winners are set to meet in Saturday s final.
As US Tennis Association officials checked the radar, the drama built around Williams and her quest for more tennis history.
The 33-year-old American, who already holds all four major titles, is chasing the first calendar Grand Slam since Steffi Graf in 1988 and trying to match Graf s Open Era career record of 22 Slam singles titles, two shy of Margaret Court s all-time record.
"There s always another record. There s always another person to catch," Williams said.
"I never really thought I would be in this position where I would even be talking about records, talking about passing Steffi Graf or even mentioning Margaret Court.
"I just grew up trying to be the best that I could and do the best that I could. I worked really hard for everything, so to even be mentioned in that conversation is great."
- Unbeaten record -
Three-time defending champion Williams, who seeks an Open Era-record seventh US Open title, has won all four career meetings against Vinci without dropping a set. She also is 7-0 against Pennetta and 6-1 against Halep in their career rivalries.
Williams has played down the one-year feat, saying she had more pressure completing her second "Serena Slam" than a calendar Slam, but she admitted as she reached the last four, "It is important to me."
Only five players have completed the calendar-year sweep of the Australian, US and French Opens and Wimbledon -- Americans Don Budge in 1938 and Maureen Connolly in 1953, Australians Rod Laver in 1962 and 1969 and Margaret Court in 1970 and Germany s Graf in 1988.
Vinci suffered her most recent loss to Williams at a Toronto quarter-final last month.
"I m not going to underestimate her," said Williams. "She has played really well. She s not in the semifinals of a Grand Slam for no reason. She knows what to do and she knows what to play.
"I just think it was great that I just played her because I kind of know what to expect, and I ll be more ready for it this time."
Vinci, 32, has already enjoyed a measure of success by reaching her first Grand Slam semi-final.
"I have a lot of experience, but when you play against Serena, doesn t matter," Vinci said. "You have to play better than better than better."
- She has a chance -
Williams is 53-2 this season and a huge favorite over Vinci but Pennetta warned not to discount her compatriot.
"I think she has a chance," said Pennetta. "She has to go in the court and try her best. You just have to go on court and try everything."
Czech fifth seed Petra Kvitova, a two-time Wimbledon champion ousted by Pennetta in the quarter-finals who beat Williams on Madrid clay in May, said she would be shocked if Williams did not win the title.
"If she is going to be in the final, I think she is going to put everything that she has inside and she is going to win it," Kvitova said.
Pennetta has won three of four meetings with Halep, including a fourth-round affair at the 2013 US Open, but lost their most recent meeting this year at Miami.
"It looks like she s not that powerful but she is," Pennetta said.
"To make a winner to her you have to finish the point seven times. She s really consistent. She s always there. The ball always come back. It s going to be like marathon."
