Saturday's US Open women's singles final between Serena Williams and Victoria Azarenka has been postponed until Sunday because of forecast heavy rains and storms in New York, organisers announced.
"The weather forecast for this evening is calling for storms with heavy rain and high winds," said a tournament spokesman.
"Due to the severe weather forecast, session 25 featuring the Women's Singles Final will be postponed until Sunday, September 9, 2012. We will confirm the start time for the Women's Final by 7:00 p.m. ET (2300GMT) this evening."
Play on Saturday had already been delayed by 90 minutes following heavy rain and a tornado warning which had been issued for the New York area.
The first men's semi-final between Andy Murray and Tomas Berdych got underway 90 minutes late on Arthur Ashe Stadium.
The second semi-final featuring defending champion Novak Djokovic and David Ferrer was still set to go-ahead as scheduled.
"We are continuing the day session as scheduled and will closely monitor the weather for the remainder of today's day session," added the spokesman.
It will be the fourth time in five years that the women's final has been played on the Sunday rather than Saturday.
The men's singles final has been pushed back to the Monday for the last four years.
British third seed Murray, the 2008 runner-up, and Berdych, who knocked out five-time champion Roger Federer in the quarter-finals, battled high winds in the first set of their tie.
In the fourth game, Murray agreed to replay a point after Berdych insisted that he had been distracted by the Scot's white cap being blown onto the court as he chased down a drop shot.
Despite the testing conditions, the earlier deluge didn't dampen everyone's spirits at Flushing Meadows.
"Supposed to interview James Blake. He's caught in the traffic & I don't want to ruin my shoes. tornado warning until 11:30 AM," tweeted 1979 and 1981 champion Tracy Austin, now working as a TV analyst.
US tennis legend John McEnroe tweeted: "A tornado warning??? You cannot be serious!!!"