Normally so good, so gritty, in the crucible of the third set, Maria Sharapova finally met her match against Victoria Azarenka in their U.S. Open semifinal on Friday. Coming all the way back from a set and a break down, the top-seeded Azarenka prevailed in a stirring third, beating four-time Grand Slam champion Sharapova 3-6, 6-2, 6-4 to reach her first U.S. Open final.

"This one didn't go my way," Sharapova said. "Frustrating, but it's the game of tennis. A lot of swings in the match today. Certainly had the lead and the advantage."

Sharapova had been 12-0 in three-setters this year, and had won 78 consecutive matches in which she took the opening set, dating back to 2010. But Azarenka broke in the last game to push her own 2012 record to 12-0 in matches that went to three. "I didn't know that statistic," Azarenka said during an on-court interview. "It's pretty good."

On Saturday, Australian Open champion Azarenka will play in her second major final of the season — and career — against 14-time Grand Slam champion Serena Williams. Seeking a fourth title at Flushing Meadows, the fourth-seeded Williams wasted little time or energy while overwhelming 10th-seeded Sara Errani of Italy 6-1, 6-2. "It's stressful against her," Errani said. "She puts a lot of pressure on you."

A year ago, Williams was stunned in straight sets in the U.S. Open final by Sam Stosur of Australia. Facing a break point at the start of the second set, Williams pounded a forehand she celebrated with her familiar yell of "Come on!" as Stosur was reaching to return the shot. The chair umpire awarded the point to Stosur, setting Williams off on a series of insults directed at the official, including, "You're just unattractive inside."

In the 2009 semifinals in New York, Williams launched into her infamous foot-fault tirade and was docked a point on match point, ending a loss to Kim Clijsters. When a reporter mentioned to Williams, who won the U.S. Open in 1999, 2002 and 2008, that nothing of that sort has happened this year, she replied: "Hey, it's not done yet."

"I did grunt once today, and I thought, 'God, I hope I don't lose the point,'" said Williams, who has lost 19 games in six matches this year. "Like I said, my goal this year was not to get in any fights." Williams, trying to become the first 30-year-old woman to win the U.S. Open since Martina Navratilova in 1987, compiled a 38-6 edge in winners against Errani.

Since a surprising exit at the French Open in late May, her only first-round loss in 49 appearances at major tournaments, Williams is 25-1, including a title at Wimbledon and gold medal at the London Olympics.

Williams has a 9-1 career record against Azarenka. "I've got to do something different, to be honest," Azarenka said. Asked whether she would watch video of their past matches, Azarenka joked: "Well, I don't want to be depressed."

Then again, the way Azarenka dealt with Sharapova, she's probably feeling pretty good about herself. She certainly looked pleased while doing a little jig after Sharapova's forehand sailed long on the final point of their 2-hour, 42-minute quarterfinal. "I was just not trying to focus on the score," Azarenka said. "Trying to give whatever it takes." Sharapova double-faulted 10 times, a recurring theme ever since she returned from surgery on her right shoulder in 2008.

"I gave her too many free points," Sharapova said. This has been a resurgent year for the Russian, who completed a career Grand Slam by winning the French Open in June, was the runner-up at the Australian Open and the Olympics, and briefly returned to No. 1 in the rankings — a spot that now belongs to Azarenka.

"I'll take the results I had this year," Sharapova said. She reached her first U.S. Open semifinal since winning the 2006 title thanks to overcoming deficits en route to three-set victories in the fourth round and quarterfinals. But she didn't have one more late-match charge in her.

When Sharapova broke Azarenka to go ahead 1-0 in the second set, she appeared to be in control. But that's when Azarenka fought back, taking four consecutive games. "All heart," said Azarenka, a 23-year-old from Belarus. "That's what I feel like we play for, we live for," Azarenka said, "to play on these big stages against such champions."