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. Stosur received a text from the former player that read: "Twinkletoes, you finally have got what you deserved."
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.
Most of all, Stosur avoided being distracted by the bizarre events that unfolded in the second set's opening game. Asderaki ruled that Williams hindered Stosur's ability to complete that point and awarded it to Stosur, putting her ahead 1-0.
Williams went over to talk to Asderaki, saying, "I'm not giving her that game."
Williams also said: "I promise you, that's not cool. That's totally not cool."
Spectators began jeering, delaying the start of the next game as both players waited for the noise to subside.
"It was probably the loudest I ever felt a crowd in my whole entire life. You're right in the middle of it. It was definitely a quite overwhelming feeling," Stosur said. "But once I hit that next ball in the court and started playing again, I felt settled. I guess it definitely could have been the big, pivotal point in the match."
The truth is, the outcome never really appeared to be in doubt.
Even Williams acknowledged as much.
"She was cracking 'em today," said Williams, whose five games matched her lowest total in 240 Grand Slam matches. "She definitely hit hard and just went for broke."
Tournament director Brian Earley said Asderaki's ruling was proper, according to U.S. Tennis Association spokesman Chris Widmaier.
International Tennis Federation rules say: "If a player is hindered in playing the point by a deliberate act of the opponent(s), the player shall win the point. However, the point shall be replayed if a player is hindered in playing the point by either an unintentional act of the opponent(s), or something outside the player's own control (not including a permanent fixture)."
Williams said later she thought the last part of the rule applied — and the point should have been replayed — such as when one player's hat flies off during a point.
"I guess the rules of tennis are there for a reason," Stosur said. "She made the call that she felt was right."
In the heat of the moment, Williams had trouble putting the whole episode behind her and continued to berate Asderaki.
The chair umpire issued a code violation warning for verbal abuse, and the USTA said Earley would speak to the Asderaki and review tape to determine whether Williams would be fined. That decision will be announced Monday.
When Stosur wrapped up the match with a forehand winner, Williams refused the customary post-match handshake with the chair umpire.
This sort of thing has happened before at the U.S. Open to Williams, who won the tournament in 1999, 2002 and 2008.
In the 2009 semifinals against Kim Clijsters, Williams was called for a foot-fault that set her off on a profanity-laced outburst at a line judge. Williams lost a point there, and because it came on match point, Clijsters won.
That led to an immediate $10,000 fine from the U.S. Tennis Association and later a record $82,500 fine from Grand Slam committee director Bill Babcock, who also put Williams on a "probationary period" at Grand Slam tournaments in 2010 and 2011, saying that fine could wind up doubled. The USTA said Babcock will determine whether what Williams said to Asderaki on Sunday is a "major event" that counts as a violation of that probation.
A poor call during Williams' 2004 U.S. Open quarterfinal loss to Jennifer Capriati was cited as a main reason for the introduction of replay technology in tennis.
"It's just always something," said Williams' mother, Oracene Price. "And it seems to happen to us."
Because of rain during this year's tournament, the women's final was pushed from Saturday night to Sunday. It was preceded by a moment of silence in memory of the victims of the Sept. 11 terrorist attacks, "9-11/01" was painted in white next to the blue court to commemorate the 10th anniversary, and the U.S. flag atop Arthur Ashe Stadium was at half-mast.
A couple of hours before stepping on court, Williams tweeted: "My Thoughts and prayers to all who lost loved ones on 9-11. I know the entire country is with you today. I'm playing for you today."
Stosur was playing in only her second major final — she was the runner-up at the 2010 French Open — while Williams was in her 17th.
"I felt like I was definitely the underdog," Stosur said.
For all of her edges in experience, Williams was the one who started a bit shakily. She was back in action less than 18 hours after winning her semifinal over No. 1 Caroline Wozniacki on Saturday night, and Williams' game was sleepy.
"It was a little bit of a tough turnaround, but I don't think it would have made a difference today," said Williams, who said she didn't fall asleep until after 4 a.m. "I just probably should have been lighter on my toes and move in a little faster."
Her serve — usually one of her top shots — was problematic, slower and less accurate than usual: Only three of her initial 14 first serves landed in, and they hovered around 160 km/h. Told she'd put 35 per cent of her first serves in play during the first set, Williams replied: "Wow. That's not so good."
Williams pushed a backhand long to get broken and fall behind 2-1. She flubbed another backhand to lose serve and make it 5-2. When Stosur smacked a forehand winner moments later, she had taken 12 points in a row and owned the first set.
That was the first set Williams had lost in seven matches during this U.S. Open, a run that included four victories over women ranked in the top 20. She said her poor play Sunday is what made her so excited when she hit the forehand that led to all the commotion.
"It was beautiful. I hit it, like, right in the sweet spot," Williams said. "It was a good shot, and it was the only good shot I think I hit. I was like, 'Woo-hoo!'"
That moment of joy didn't last long.
Entering the final, Williams was 18-0 on hard courts this season, a full-throttle comeback after missing nearly a year because of health scares, including cuts on her feet from glass at a restaurant, two foot operations, clots in her lungs and a gathering of blood beneath the skin of her stomach.
She was ranked 175th after a fourth-round exit at Wimbledon, but hadn't lost since then until Sunday and was seeded 28th at the U.S. Open.
"It's been an arduous road. Six months ago in the hospital, I never thought I'd be standing here today," Williams said. "I didn't think I'd be standing, let alone here."
Stosur dealt with her own health issues that could have sidetracked her career, and she became the oldest U.S. Open champion since Martina Navratilova was 30 in 1987.
Once a doubles specialist — she's won Grand Slam titles in women's and mixed — Stosur only once got past the third round in singles at a major tournament before reaching the 2009 semifinals at the French Open.
Her game has improved dramatically since she returned to the tour in April 2008 after about nine months away while recovering from Lyme disease, a tick-born illness that can affect a person's joints and nervous system. She was ranked 149th two years ago; on Monday, she'll rise to No. 7.
"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 fulfil that."