NEW YORK (AP) — That Maria Sharapova's shaky serving contributed to her early exit at the U.S. Open — to the tune of a dozen double-faults — came as no surprise. She's faced that problem for quite some time.
That Sharapova's other strokes also were problematic Friday could be explained away by the perpetual motion of her opponent in the third round, 26th-seeded Flavia Pennetta of Italy.
That three-time major champion Sharapova's nerve would fail her in the crucible of a third set? Now that was the real stunner.
Unbeaten this year in 12 previous matches that went the distance, the third-seeded Sharapova faltered down the stretch and dropped the last seven points of a 6-3, 3-6, 6-4 loss to Pennetta that took 2½ hours.
"She's a good fighter, you know. You can never give up with her. You have to be focused until the last game; until the last point, actually," Pennetta said. "But I think (at) 5-4, she's starting to feel a little bit of pressure."
After trailing 3-0 and 4-1 in the last set, Sharapova turned things around briefly, getting to 4-all, 15-30 on Pennetta's serve. But the 2006 U.S. Open champion wouldn't win another point.
"I came back. I had chances. There's no doubt I had chances," Sharapova said. "But I guess today was the day I didn't take them."
Aside from all of those double-faults — including two to begin the final game — Sharapova finished with a total of 60 unforced errors, twice as high as her winner count.
"I didn't feel comfortable with most of my game today," Sharapova said.
Because of her Grand Slam pedigree and recent play, she was seen as someone who'd stick around deep into the second week at Flushing Meadows. Instead, Sharapova joined the reigning Wimbledon (Petra Kvitova) and French Open (Li Na) champions in leaving quickly, while two-time defending U.S. Open champion Kim Clijsters didn't enter because of injury.
The man most consider the best without a major championship, No. 4 Andy Murray, appeared on his way out, too, after losing the first two sets against 41st-ranked Robin Haase of the Netherlands. But with Haase getting treated by a trainer for back problems between sets, Murray came all the way back to win 6-7 (5), 2-6, 6-2, 6-0, 6-4.
Murray was asked how he reversed course.
"I started chasing a lot of balls down," said the three-time Grand Slam finalist, who now faces No. 25 Feliciano Lopez, the player he beat in the quarterfinals at Wimbledon. "At the beginning, I felt sluggish, felt slow. I started forcing myself to get every single ball."
That's what defending champion Rafael Nadal generally appears to do on every point of every match. After a tough test in the first round, he didn't need to scramble all that much in the second, though, building a 6-2, 6-2 lead before Nicolas Mahut quit because of an abdominal injury he said prevented him from serving at full strength.
Asked to assess Nadal's form, Mahut replied: "Maybe he doesn't have as much confidence as he had last year. ... But with Rafa, you never know."
Next for Nadal is 2002 Wimbledon finalist David Nalbandian, who knocked out 30th-seeded Ivan Ljubicic 6-4, 1-6, 6-3, 6-2.
Nadal's predecessor as U.S. Open champion, 18th-seeded Juan Martin del Potro, easily advanced, while other winners during the day session included three Americans: Donald Young, who upset No. 14 Stanislas Wawrinka of Switzerland 7-6 (7), 3-6, 2-6, 6-3, 7-6 (1); and No. 28 John Isner and Alex Bogomolov Jr., who'll face each other in the third round.
In an all-American matchup at night, 2003 U.S. Open champion Andy Roddick beat 18-year-old Jack Sock 6-3, 6-3, 6-4. Roddick, who's seeded 21st, converted all five break points he earned and saved all but one of the seven he faced.
Still, Sock got a chance to show off some of the skills and moxie that helped him earn a wild card at Flushing Meadows each of the last two years by winning the boys' national championship — and that have made some peg him as his country's next tennis star.
"Three years ago, four years ago, I started hearing about this kid from Nebraska," said Roddick, who like Sock was born in that state. "He was gangly, hit the ball hard. ... It all sounded too familiar. I'm really excited about the future of American tennis. It is bright."
The 22-year-old Young has been marked for greatness since he was a teen, but his results haven't lived up to that hype.
"I'd like to think I'm a pretty tough person, deep down," the 84th-ranked Young said. "I just had to grow up a little bit. Everybody's light goes on at a different time. Hopefully, mine's coming on right now."
Young drew attention this year for an obscenity-laced tweet directed at the U.S. Tennis Association over its decision not to give him a wild card into the French Open. Patrick McEnroe, the head of player development for the USTA, took to Twitter as Young's victory wrapped up Friday, writing: "In tennis terms, Donald Young became a man today."
Before Roddick and Sock took the court in Arthur Ashe Stadium, 19-year-old Christina McHale of Englewood Cliffs, N.J., lost 6-2, 6-3 to No. 25 Maria Kirilenko of Russia. Earlier, another young American, Irina Falconi, was beaten 6-0, 6-1 by No. 22 Sabine Lisicki of Germany. McHale and Falconi had upset seeded players in the second round, but put up little resistance in the third.
In other women's matches, 2010 Wimbledon and U.S. Open runner-up Vera Zvonareva beat No. 30 Anabel Medina Garrigues 6-4, 7-5, No. 9 Sam Stosur edged No. 24 Nadia Petrova 7-6 (5), 6-7 (5), 7-5, and No. 13 Peng Shuai defeated No. 19 Julia Goerges 6-4, 7-6 (1).
Peng will take on Pennetta, a doubles champion at the Australian Open in January and a two-time U.S. Open quarterfinalist who covered every inch of the court and kept extending points against Sharapova.
"She played really smart," Sharapova said. "That's her game, and she makes you hit a lot of balls."
Pennetta was unaware of Sharapova's 12-0 mark in third sets entering the day (the Italian was 9-7). But she did know she could count on Sharapova to miss her share of serves. When a reporter began to ask about Sharapova's late double-faults, Pennetta interrupted to point out, "I was happy."
Ever since returning to the tour after October 2008 surgery on her right, racket-swinging shoulder, former No. 1 Sharapova has worked to reshape her serve and return to the top of tennis. And she did appear to be back to — or at least near — her best in recent months, winning titles at Rome on clay and Cincinnati on hard courts, reaching the semifinals at the French Open and the final at Wimbledon.
But a pattern developed, too: In her loss at Roland Garros, for example, she hit 10 double-faults, including on match point. In her semifinal victory at the All England Club, she overcame 13 more.
So Pennetta explained she wanted to be "really aggressive" on returns "to just let her think too much and maybe make some double-faults. That's what happened."
Follow Howard Fendrich at http://twitter.com/HowardFendrich