Six months after she nearly died, Serena Williams finds herself carrying the hopes of a grieving nation at the US Open.

By a twist of fate, the women's singles final was moved from Saturday to Sunday, coinciding with the 10th anniversary of the September 11 attacks.

Had the men's final been held on Sunday as originally scheduled, the US would not been represented but the switch, caused by two days of rain, has thrust Williams into the spotlight on a day when emotions will already be running high.

"I really wanted to get here and get to the final," she said after beating World No. 1 Caroline Wozniacki 6-2, 6-4 in Saturday's semi-finals, which ended 17 hours before the final.

"Everything that New York and Americans have been through...it's hard to believe it's been 10 years."

Williams also played in the final 10 years ago but lost to her older sister Venus. Her opponent this time is Australia's Sam Stosur, who sealed her place with a 6-3, 2-6, 6-2 win over unseeded German Angelique Kerber.

Stosur has never won a grand slam before but is appearing in her second final. She saved a match point to beat Williams at the French Open last year but lost the final to Francesca Schiavone.

"It's great that now I've got a second chance to try and win one of these titles," Stosur said.

"I know it's going to be extremely difficult and I'm going to have to play really well to try and win but that's what you play for and you want to get into these situations."

The importance of the occasion has not been lost on the Australian. New York is on high-alert for the anniversary and security at the National Tennis Center will be beefed up with the deployment of extra police and sniffer dogs.

"To be playing a final on that day, there's going to obviously be a lot of sadness and everything else," Stosur said.

"But it's also, you know, a great day for us to be playing the finals.

"It's a time to remember what happened, but also to maybe get through it. And hopefully we can have a good match."

As the dominant player of her generation, Williams is the overwhelming favourite.

The 29-year-old has won 13 grand slam singles titles, including three US Opens, and has been in great form, despite only recently returning to the sport after a series of health problems that began when she badly cut her foot on broken glass at a restaurant in Germany after she won last year's Wimbledon title.

She and underwent two operations because of complications with the injury then developed a life-threatening on her lungs that doctors discovered in the nick of time.

"I really feel like I don't have anything to lose. I have beaten all odds," she said.

"Six months ago I was in the hospital and now I'm in the final so I feel like regardless of a result, I have just been a champion for everyone out there who are fighting against all odds."

Despite that, Williams still has her sights set on the title but is wary of Stosur, who is not only one of the biggest hitters in the game but also won the toughest fighters, as Williams discovered at the French Open.

"I was really upset because I had a match point and those are always the hardest defeats," Williams said.

"Sam's such a fighter...but I learned a lot. After that I went on to win Wimbledon because of that loss."