New York ? Even before she began berating the chair umpire, things were not going well for Serena Williams in the U.S. Open final.

Her strokes were off-target. Her opponent, Sam Stosur, was playing better than ever. And Williams’ deficit was growing more and more daunting.

So facing a break point at the start of the second set Sunday night, Williams ripped a forehand that she celebrated with her familiar yell of “Come on!” The problem, it turned out, was she screamed as Stosur was reaching for a backhand, so the point wasn’t finished. The chair umpire awarded the point to Stosur, setting Williams off on a series of insults directed at the official, a scene far less ugly than — yet reminiscent of — the American’s tirade at the same tournament two years ago.

In the end, Stosur’s powerful shots and steadiness allowed her to beat Williams 6-2, 6-3 in a surprisingly lopsided upset for her first Grand Slam title. Stosur left the court as the U.S. Open champion; Williams’ night ended with her facing possible disciplinary action.

A sampling of what Williams said to chair umpire Eva Asderaki:

— “You’re out of control.”

— “You’re a hater, and you’re just unattractive inside.”

— “Really, don’t even look at me.”

Asked at her news conference whether she regretted any of her words, the 13-time Grand Slam champion rolled her eyes and replied: “I don’t even remember what I said. It was just so intense out there. … I guess I’ll see it on YouTube.”

She won’t be the only one, for sure.

Stosur probably will prefer to watch footage of some of the points she dominated.

“I’m still kind of speechless. I can’t actually believe I won this tournament,” Stosur said later, the silver U.S. Open trophy sitting a few feet away. “I guess to go out there and play the way I did is obviously just an unbelievable feeling, and you always hope and you want to be able to do that, but to actually do it, is unbelievable.”

The ninth-seeded Stosur became the first Australian woman to win a major championship since Evonne Goolagong Cawley at Wimbledon in 1980.

Only 2-9 in tournament finals before beating Williams, Stosur made the U.S. Open the third consecutive Grand Slam tournament with a first-time women’s major champion, after Li Na at the French Open, and Petra Kvitova at Wimbledon.

This was only the 27-year-old Stosur’s third title at any tour-level event, and what a way to do it. She took advantage of Williams’ so-so serving and finished with 12 unforced errors to Williams’ 25.