That means the women will now have to play the semifinal and the final on consecutive days, with Pennetta and Halep opening up play on Friday morning.
While Halep has done well to justify her No.2 seeding – the win over Victoria Azarenka was particularly impressive – there will now be pressure on the Romanian to ease past the No.28 seed.
In the second women’s singles match, Serena will start as the overwhelming favourite, with Vinci playing in her first ever Grand Slam semifinal.
Once the women’s action is done, there will be enough time for that sense of anticipation to reach fever pitch, before the men take court for their own semifinal matches.
First up in the evening/night session is Novak Djokovic vs Marin Cilic, with the world number one looking to end the defending champion’s run.
Djokovic has had a couple of hiccups – by the Serbian’s own ridiculously high standards – in the last two rounds, and this Cilic match should provide another stiff test.
After the Djokovic vs Cilic match, we will have the all-Swiss clash between Roger Federer and Stan Wawrinka. Wawrinka has to try and do something he hasn’t managed before if he is to stop Federer in the semifinals – beat his compatriot on a Grand Slam court not made of clay.
That will be easier said than done, because Federer has been sublime, and then some, in this US Open 2015. Wawrinka has been much more of a slow burner, but all that power and finesse was on show when he vanquished Kevin Anderson, the conqueror of Andy Murray, in three sets in the quarterfinals.
In Indian interest, we have Leander Paes and Martina Hingis looking to win a second consecutive Grand Slam title together in the mixed doubles. Paes and Hingis haven’t had to play too much at this US Open, but when they have, they’ve been pretty impressive.
The Indian-Swiss pair will have to overcome Americans Bethanie Mattek-Sands and Sam Querrey as well as the crowd if they are win a third Grand Slam title of 2015.
The first semi-final, featuring Simona Halep and Flavia Pennetta, will now start at 11am ET (4pm BST) on Friday with Williams’s match following afterwards. Williams is attempting to become the first female player since Steffi Graf in 1988 to win the Australian Open, French Open, Wimbledon and US Open in a calendar year.
The postponements mean that the men’s semi-finals will now start at 5pm instead of 3pm on Friday. Novak Djokovic is first on court against Marin Cilic, while Roger Federer plays fellow Swiss Stan Wawrinka afterwards.
