NEW YORK (Reuters) - Caroline Wozniacki became the highest seed to fall in the upset-filled women's draw at the U.S. Open when Czech Petra Cetkovska stunned the Dane 6-4 5-7 7-6(1) at Flushing Meadows on Thursday.
The upset left only three of the top 10 seeds still alive in the year's final grand slam - number one Serena Williams, who is seeking the fourth women's calendar-year Grand Slam, second seed Simona Halep and fifth seed Petra Kvitova.
Cetkovska, who has tumbled to a 149th ranking after missing seven months with a hip injury before returning in March, was playing in the Open thanks to a special injury exemption.
She rode a powerful forehand that produced 29 of her 61 winners to victory over Wozniacki, saving four match points held by the Dane - all on winners off her racquet.
"I said it's now or never, so I just went for it," she said in an on-court interview about her string of match point saves. "It's just amazing."
"So happy to be able to be back and to compete," said the 30-year-old Cetkovska, who will play Italy's Flavia Pennetta, a straight sets winner over Romanian Monica Niculescu.
Former world number one Wozniacki, a finalist last year, was naturally dejected.
"She played well. I let her play well," Wozniacki, 25, said. "She had nothing to lose and went for her shot.
"It could have gone my way. I'm just frustrated with the match," she added. "Not playing my best level, but still being so close, still having my chances, not closing it out. That hurts. That really hurts."
The Czech said she was spurred on by the Arthur Ashe Stadium crowd. "The atmosphere, it's (like) nowhere else. It was just keeping me alive. I wanted to fight to the end," she said.
The three-hour match which closed Thursday's play at the U.S. National Tennis Center featured wild swings of momentum.
Wozniacki, a two-times U.S. Open finalist, won the first three games and led 4-2 before Cetkovska ran off seven games in a row to win the set, and took a 4-1 lead before the Dane won six of the next seven games to force a third set.
The last set featured intense rallies, with Cetkovska saving one match point to hold for 5-5 and three more in the 12th game to set up the tiebreaker.
From that point on, the Czech dominated, winning the last six points to complete the shock victory.
It was not the first time Cetkovska had upset Wozniacki. The Czech also beat her 6-2 6-2 in the second round at Wimbledon in 2013.
Cetkovska, who ranked as high as 25th in 2012, had hip surgery in September last year and wondered if she would ever play big-time tennis again.
"Those first months it was extremely difficult," she said. "Every day I was asking myself if I will be able to play tennis again, to play on such a big stadium, to play such a big match and win it.
"So for me, it's just an amazing feeling."
Editing by Amlan Chakraborty