The heavy rain came as expected here Thursday, meaning Friday's U.S. Open tournament will feature four semifinals, not just the men's two.
They used to have a Super Saturday, and now that will be a day earlier. Next year there will be a roof to prevent postponements.
The big deal remains Williams, who can move to within one victory of a calendar Grand Slam. That theme has dominated this tournament.
Williams is No. 1 and looking for her 22nd major title, and, most likely, relief from the pressure of this long pursuit. Her opponent, Vinci is ranked No. 43 and known to win mainly with spins and slices. She has said to beat Williams she will have to play "better than better than better."
She also joked, playing against Williams' power, she might consider wearing a helmet.
The opponent for Williams' likely appearance in Saturday's final is less certain. Halep is No. 2, but not considered to be a threat to Williams. Halep is 5 feet 3 and, according to Pennetta, has more power than she appears to have.
"She looks not as powerful as Vika but she is," Pennetta said, referring to Victoria Azarenka, the player Halep beat in the quarterfinals. "More powerful, I think."
The men's semifinals brings with it 29 major titles.
Federer has 17 of those, and even at 34, his march to the semifinals without the loss of a set makes him at least the co-favorite, along with No. 1 Djokovic.
But first, Federer needs to get past countryman Stan Wawrinka, who beat him on clay in Roland Garros this year and who has always commanded respect from Federer.
"I always thought Stan was a better player than his record showed," Federer said.
Wawrinka's record started to improve when he won the 2014 Australian, and now, as the No. 5 seed, he is beginning to feel as if he belongs, despite his shyness and tendency to always defer to Federer as the "best ever."
Djokovic, of Serbia, added two majors to his previous total of seven this year (Australian and Wimbledon). He has struggled more than Federer, the No. 2 seed, and needed four sets in two consecutive late-night matches to get to these semifinals.
Djokovic beat Federer in the last two Wimbledon finals, but lost to him recently in the final of a Masters Series event in Cincinnati.
Djokovic's path to the final will not be a breeze. His opponent, Cilic, won his first major title here last year. As the No. 9 seed, the Croatian has floated under the radar most of this tournament until his quarterfinal match with the flashy Jo-Wilfried Tsonga of France.
It took Cilic five sets and five match points to finally win, and yet, with his huge serve and huge forehand, he will not be a pushover for Djokovic, who beat him in straight sets this year at Wimbledon.
Last year, the Djokovic-Federer final was much anticipated. It never happened.
In the semifinals, Djokovic was beaten by Japan's Kei Nishikori and Federer by Cilic.