On a bad day for seeded players on Daniel Island, world No. 1 Caroline Wozniacki was happy just to survive -- even if she needed 2 1/2 hours and two tiebreaks to do it.

In a Stadium Court match that surely entertained ESPN2 viewers, the top-seeded Wozniacki outlasted Barbora Zahlavova Strycova 7-6 (6), 7-6 (9) to make the quarter-finals of the Family Circle Cup.

"It was a bit difficult for me today," Wozniacki conceded after the match. "I'm happy to have pulled it through."

That's far more than four other top seeds could say after Thursday's upsets. Defending champ Samantha Stosur, seeded No. 2, and No. 5 Shahar Peer, No. 7 Nadia Petrova (the 2006 champ) and No. 10 Daniela Hantuchova all were eliminated, Hantuchova falling in straight sets to rising American standout Christina McHale.

Sabine Lisicki, the 2009 Family Circle champ, went out in straight sets to qualifier Sania Mirza of India. Third-seeded Jelena Jankovic was able to advance with a 6-2, 6-2 win over Chanelle Scheepers in Thursday's late match.

McHale's 7-6 (3), 6-1 win over the 33rd-ranked Hantuchova was a career

highlight for the 18-year-old American, who is ranked No. 97 and will make her Fed Cup debut for the U.S. team against Germany next week.

Her recent success has placed McHale alongside Melanie Oudin and Bethanie Mattek- Sands in the second tier of American players behind Venus and Serena Williams.

"There's a whole group of us Americans that are trying to break through right now," said McHale, who began to play tennis as a child when her family lived in Hong Kong. "I'm just playing my best and just seeing how it goes."

Wozniacki's day could have gone a lot differently if the 25-year-old Zahlavova Strycova, from Czech Republic, could have converted set points in each set.

"If you don't make those set points, it's tough to win these matches," said Zahlavova Strycova, who had to deal with a mid-match nose bleed. "I played pretty good and I didn't make it, so it hurts a lot."

Wozniacki, who will face sixth-seeded Belgian Yanina Wickmayer in the quarter- finals, said she could have made things easier for herself.

"I had chances in every single game to finish off the set easy, but I missed a few shots that I shouldn't have missed," said Wozniacki, who led 4-1 in the first set. "And suddenly, she's back in the game. She's getting everything back and she's playing very well."

In the second set tiebreak, Wozniacki needed five match points to finish off the No. 48 player in the world, who lamented her missed opportunity.

"I am happy (with my performance)," Zahlavova Strycova said. "But it hurts if you can actually win these matches and you don't do it. She's a great player, and you can beat a player who is No. 1 in the world. You can play great, but if you don't win, I am sad. But I was playing my best."