WIMBLEDON, England – A year that started with another Grand Slam-tournament title for Li Na of China has turned into a major disappointment.

On a day when top-seeded Novak Djokovic of Serbia had a nasty-looking fall, defending champion Andy Murray of Britain easily advanced and five-time champion Venus Williams of the United States lost, Australian Open winner Li was eliminated 7-6 (7-5), 7-6 (7-5) in the third round by Barbora Zahlavova Strycova in perhaps the biggest upset this year at Wimbledon.

At the French Open, where she won her first major singles title in 2011, Li was beaten by Kristina Mladenovic of France in the first round. The second-seeded Li, who did not play in any of the grass-court warm-up tournaments earlier this month, looked out of sorts for most of the match Friday.

“I think I made a wrong decision, I needed to play some matches before the big one,” said Li, who failed to convert a set point in the second set against the 43rd-ranked Zahlavova Strycova, who is from the Czech Republic.

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“When you go on court you have to believe in yourself,” said Zahlavova Strycova, who called the victory the biggest of her career.

No. 30 Williams lost 5-7, 7-6 (7-2), 7-5 to 2011 Wimbledon winner Petra Kvitova of the Czech Republic. Kvitova is seeded sixth.

Djokovic overcame a hard fall in the third set to advance to the fourth round with a 6-4, 6-2, 6-4 Centre Court decision over Gilles Simon of France.

Leading 3-2 in the third set and with Simon serving, Djokovic lunged for a forehand shot and fell hard to the grass, rolling over and grabbing his upper left arm and grimacing in pain.

But after taking a medical timeout and receiving treatment from a trainer, he recovered to play out the final four games of the match, breaking Simon’s serve in the final game, his seventh break in the match.

“I basically had a strong impact on the shoulder,” Djokovic said. “When I stood up, I felt that click or pop. I feared maybe it might be a dislocated shoulder … or joint problem.

“But luckily for me it was only an impact that had a minor effect on the joint and the muscles around, but no damage, significant, that can cause a bigger problem. I just came from the doctor’s office, ultrasound. It’s all looking good.”

Murray, also playing on Centre Court, beat Roberto Bautista Agut of Spain 6-2, 6-3, 6-2 and hasn’t dropped a set this tournament.