Australia's Sam Stosur won her first Grand Slam title - but her US Open victory was overshadowed by Serena Williams's verbal abuse of the umpire.
The ninth seed gave a hugely impressive performance to win 6-2 6-3.
But Williams is facing a fine after telling umpire Eva Asderaki: "You're out of control" and "You're a hater, and you're just unattractive inside."
The 13-time Grand Slam champion was upset at Asderaki for awarding a point to her opponent.
Facing a break point in the second set, Williams looked to have saved it with a forehand winner.
But her loud cry of "Come on!" was judged by Asderaki to have come before Stosur had a chance to get the ball back, and the point - and the game - went to the Australian.
Williams was furious, staring at the umpire in disbelief as the feisty New York crowd let their feelings be known. After hitting a winner on the subsequent point, the American aimed the angry tirade at Asderaki.
She was consequently given a code violation, and at the end of the game she continued to berate the umpire, saying "you're out of control" and "you're unattractive inside", among other things.
The whole episode could later be significant as Williams is still playing under a suspended ban for another incident at the US Open two years ago.
Stosur, 27, from Queensland becomes the first Australian woman to win the US Open since Margaret Court in 1973.
She defeated Williams in one hour and 13 minutes at Flushing Meadows.
"I had one of my best days and I'm very fortunate that I had it on this stage in New York," said Stosur.
"Ever since I started playing it was a dream of mine to be here one day. I don't really know what to say. Serena, you are a fantastic player, great champion and have done wonders for our sport."
Stosur went into the final as a considerable underdog, having played in just one Grand Slam final compared to the 13-time major winner Williams, who had not dropped a set in the tournament.
She was clearly not concerned by any of that as she used her strengths, a heavy kick serve and powerful forehand, to take control against a misfiring Williams.
The American has the best serve in the game but making just 35% of first serves in the opening set allowed Stosur to attack the returns and break twice as she took it in 31 minutes.
A frustrated Williams threw her racquet to the ground as the set slipped away, but that was nothing compared to the anger she displayed early in the second.
The incident clearly energised Williams for a period as she broke back immediately with her best play of the match, but it would not last.
But the Australian stuck to her tactics, moving Williams around and attacking whenever possible, and she regained the advantage at 4-3 before moving confidently to the verge of a major shock.
There was no respite for the Williams serve as Stosur continued to attack it mercilessly, seeing two match points disappear before running around her forehand and hammering a return winner on the third.
It was just reward for a brilliantly executed game plan, while Williams' impressive return to a Grand Slam final after a year of injury and illness was certainly overshadowed by her outburst.
"It wouldn't have made a difference," Williams said when asked on court afterwards about the point she lost.
"Six months ago in the hospital I couldn't even stand up, but thanks to my parents and sisters and everyone else I'm here. I'm emotional, I might start crying. I'm happy to be here, it's really good."