NEW YORK -- Grit was not going to be enough to get Maria Sharapova through this one.

Not with nine double faults, including three in a row.

Not with a total of 36 unforced errors.

Caroline Wozniacki celebrated Monday after eliminating likely the greatest threat on her side of the U.S. Open bracket. Al Bello/Getty Images

And certainly not with No. 1-seeded Caroline Wozniacki of Denmark across the net Monday in the fourth round of the U.S. Open, doing "what she does best," as Sharapova herself put it: getting to nearly every ball and hammering it back, stretching points on and on and on until her opponent misses the mark.

It added up to a 6-3, 6-4 victory for 2009 U.S. Open runner-up Wozniacki over Sharapova, who has failed to make it even as far as the quarterfinals at Flushing Meadows since winning the 2006 title.

"I felt like I was playing well out there," Wozniacki said, then made sure everyone understood a key concept by adding, "I made her do those errors."

Indeed, she did. Rare is the opponent who can trade powerful baseline groundstrokes with three-time Grand Slam champion Sharapova and figure out a way to put her on the defensive, but that's exactly what Wozniacki managed to do as early evening shadows crept across the blue court in Arthur Ashe Stadium.

"When she had the opportunity to step in," the 14th-seeded Sharapova said, her voice a barely audible monotone, "she took it and went for her shots."

It's the first victory for Wozniacki in three career meetings against Sharapova, but they hadn't met since 2008. In that time, the 20-year-old Wozniacki has grown as a player and built a huge supply of confidence, thanks to her Grand Slam final debut in New York and, most recently, her 18-1 record since Wimbledon.

"I've improved a lot, not only physically, but also I believe in myself more. I believe I can do it," said Wozniacki, who is ranked No. 2 but received the top seeding at the U.S. Open because No. 1 Serena Williams withdrew. "Also, I think I can mix up my game a little bit more."

Wozniacki has lost only 10 games so far; no one has conceded fewer en route to the U.S. Open quarterfinals since 1999. But here is what might be the most remarkable statistic of all: After making only 10 unforced errors against Sharapova, Wozniacki has made 40 in four matches, and her opponents have made 123.