Australia's Sam Stosur upset American Serena Williams 6-2 6-3 on Sunday to win an ill-tempered U.S. Open women's final.

Stosur played the match of her life to defeat the most formidable player of her generation and capture her first grand slam title, spoiling American hopes of a home-bred champion on the 10th anniversary of the September 11 attacks.

Williams, bidding for a fourth U.S. Open crown, failed to reproduce her best after sailing to the final without dropping a set and let her frustrations boil over.

Throughout the second set she repeatedly argued with the chair umpire in a petulant display that rekindled memories of her exit from the 2009 U.S. Open.

If you ever see me walking down the hall, look the other way because you're out of control, Williams said.

While Williams berated the official, Stosur remained a model of composure. The 27-year-old dominated the match from the outset and fully deserved her win, played in front of a raucous Arthur Ashe Stadium crowd.

She put Williams under pressure from the start with some thunderbolt returns that pinned Williams behind the baseline and attacked her backhand, forcing her to make errors.

Stosur broke Williams's serve twice in the first set then three times in the second and only lost her own serve once.

Stosur, seeded ninth, became the first Australian woman to win the U.S. Open title since Margaret Court in 1973. The last Australian woman to win any grand slam was Evonne Goolagong-Cawley at Wimbledon in 1980.

Stosur, who was better known as a doubles player, emerged as Australia's best prospect in years when she made the final at the French Open last year but lost to Italy's Francesca Schiavone.