Hormone imbalance, maybe?

Karen Crouse has the story in The New York Times:

Samantha Stosur endured the longest women’s match in tournament history in one round and the longest tie breaker in another on her way to the United States Open final. When the rain came in the second week, she endured being moved like a pawn around the National Tennis Center. All the adversity— the tough opponents and tropical storms Irene and Lee— steeled Stosur for the worst storm she would have to weather on the way to her first Grand Slam title: another outburst by the three-time champion Serena Williams. For the second time in three years, Williams’ menacing behavior toward an official at Arthur Ashe Stadium overshadowed her opponent’s brilliance. In 2009, Williams lashed out at a lineswoman who called her for a foot fault and lost her semifinal to the unseeded Kim Clijsters when she was given a point penalty on match point.
In Sunday’s final, Stosur defeated Williams, 6-2, 6-3, for her first major championship. She became the first Australian woman to win a major title since Evonne Goolagong Cawley at Wimbledon in 1980. “I can’t actually believe I won this tournament,” said Stosur, 27. “To go out there and play the way I did is obviously just an unbelievable feeling.” Her feathery backhand slices and ferocious forehands will not soon be forgotten, nor will Williams’ outburst, directed at the chair umpire Eva Asderaki, which changed the tenor, if not the thrust, of the match.
It happened in the opening game of the second set. Williams had served miserably in the first set, putting 35 percent of her first attempts into play on her way to being broken twice. And she was facing another break point, at 30-40. Stosur had reeled off twelve consecutive points to secure the first set, so when Williams ripped a forehand to Stosur’s backhand for an apparent winner to stave off another break, she could not contain her glee. “Come on!” she screamed.
But Stosur stuck out her racket and got a piece of the ball, and when she made contact, it brought into play the hindrance rule. That rule also cost Marion Bartoli a point under similar circumstances in her second-round match against Christina McHale. The scoreboard initially flashed 40-40. Asderaki was slow to inform the crowd that the point and the game had gone to Stosur because Williams had verbally hindered her opponent’s ability to complete the point. The confusion whipped the crowd into a frenzy, the boos and catcalls becoming so voracious that Stosur waited to deliver her first serve of the second game until the noise died down. She bounced a ball on her racket while a defiant Williams stood on the baseline, her left hand on her hip. After Williams won the first point with another stinging forehand, she walked toward Asderaki and, pointing her racket as if it were an extension of her index finger, said something that drew her a code violation from Asderaki. During the changeover two games later, Williams continued to take Asderaki to task, and she got personal. “If you ever see me walking down the hall, look the other way,” Williams said. “You’re out of control. You’re a hater and you’re unattractive inside.” Williams continued: “Code violation for this? I expressed who I am. We’re in America, last time I checked.” The USTA said it was reviewing the incident.
Asked about it in her postmatch news conference, Williams said she was “just in the zone” at the time and did not remember what she had said. “It was just so intense out there,” she said, adding that she misunderstood the rule. “I thought it was the hat-drop rule, where if you drop a hat you kind of replay the point,” she said.
The fans fed off Williams’ ire, their decorum disintegrating after she lost her composure. Spectators started applauding Stosur’s faults and shouting during points. The crowd’s fury seemed to take Stosur out of her comfort zone, something that Williams, to that point, had been unable to do.
Stosur had not faced a break point in the first set, but she was broken in her first service game after the controversial call. After Williams held, Stosur faced two break points in the next game.
Until recently, Stosur had a reputation for being physically fit and mentally fragile. Williams, a thirteen-time Grand Slam singles champion, had won four of their six previous meetings, with one of her victories coming in Sydney in 2009 when Stosur held four match points.
Would Williams’ outburst have the dual effect of lighting her fire and dousing Stosur’s? Serving at 15-40 in the critical fourth game, Stosur climbed back to deuce by producing a 111-mile-per-hour ace and a forehand that Williams could not pick up. Four points later, Stosur served a 108-m.p.h. ace to hold. “For sure, it was difficult to stay focused,” Stosur said, “and then obviously the crowd got heavily involved. You know, it was probably the loudest I ever felt a crowd in my whole entire life. It was definitely an overwhelming feeling. But once I hit that next ball in the court and started playing again, I felt settled.”
After Stosur held for 2-2, Williams’ fury dissipated and an air of resignation settled over the crowd. Williams saved two match points on her serve, but Stosur earned a third and struck a forehand winner off a 71-m.p.h. serve.
When Williams lunged for the backhand and missed, Stosur dropped her racket and fell to her knees. Williams came around the net to wrap her in a congratulatory hug, but did not shake Asderaki’s hand. Williams sat staring into the distance as Stosur climbed into her guest box to embrace her relatives and friends. As the court was being prepared for the awards ceremony, Williams plopped down on the seat next to Stosur and, according to Stosur, said: “How do you feel? Are you really excited?”
Williams, 29, later spoke of how simply making it to the final felt like a great gift after what she had endured since her last Grand Slam championship appearance, her 2010 victory at Wimbledon. Over the next nine months, she had two foot operations and was hospitalized for a pulmonary embolism. The Open was only her sixth tournament of the year.
Stosur has had her own health issues. She was slowed to a crawl by Lyme disease in 2007 and 2008. It could have killed her career; instead, she came back mentally stronger. “It kind of made me open my eyes more that you don’t necessarily always get a second chance,” Stosur said. “I wanted to take every opportunity I had, and I have now been able to fulfill that.”

Rico says that, given the consistency of Williams' outbursts, someone oughta check that woman's blood for something...