(CNN) -- Australian Open champion Li Na bowed meekly out of Wimbledon Friday to extend her miserable record at the grass court grand slam, blaming her lack of preparation for a shock defeat.
The Chinese second seed was beaten 7-6 7-6 by Barbora Zahlavova Strycova of the Czech Republic, ranked 43 in the world, who was reaching the last 16 of a grand slam for the first time in 32 attempts.
Trailing 6-5 in the second set tiebreaker, Li successfully challenged after her forehand was called long.
But given a second chance of redemption on a replayed match point, Li served her seventh double fault to exit in lame fashion.
The 32-year-old Li has never gone beyond the last 32 in eight appearances at the All England Club and also went out in the first round of the French Open last month.
It's a far cry from her triumph in Melbourne back in January when she beat Dominika Cibulkova in the final of the opening grand slam of season, her second triumph in one of tennis' four majors.
After her defeat, Li told reporters that she had made an error of judgment in skipping the warmup event at Eastbourne. "I think I needed some matches before the big one, I think I made the wrong decision," she said.
For the 28-year-old Zahlavova Strycova, it was her biggest win of a mediocre career on the WTA Tour, interrupted by a six-month ban for a doping offense in 2013.
"I am very happy. I played a great match and I believed I could do it. It's my biggest win," she said.
Former world number one Caroline Wozniacki awaits the Czech in the next round, the Dane beating Croatian teenager Ana Konjuh 6-3 6-0 to reach the last 16 of a grand slam for only the third time since 2011.
Petra Kvitova later won the battle of former champions on Centre Court after an enthralling two and a half hour battle against Venus Williams.
Kvitova, who took the title in 2011, had to come back from a set down to beat the five-time champion from the United States, 5-7 7-6 7-5.
Polish fourth seed Agnieszka Radwanska, the runner-up to Venus' younger sister Serena in 2012, also made the last 16 with a 6-2 6-0 win over Portuguese qualifier Michelle Larcher de Brito.
In the men's tournament, top seed Novak Djokovic took a nasty tumble on the way to a 6-4 6-2 6-4 win over France's Gilles Simon.
The 2011 champion made a spectacular diving attempt to reach a Simon shot in the sixth game of the third set and fell awkwardly on his shoulder.
The Serbian star needed treatment on the court and had to take a painkiller before rounding out an otherwise routine win.
"Yes it was a sharp pain when I fell. It was an awkward fall. I was just hoping nothing was going on bad with the joint," he admitted later to reporters.
"There was no damage in the joint, so I could play a few games after that. The muscle was still quite sore because of the impact, so all in all I'm just glad to get through.
"Now there are two days off so I'm going to recover and get ready."
Djokovic faces a tough last 16 clash against Jo-Wilfried Tsonga, but has won 10 of his 11 meetings with the Frenchman, who is seeded 14th this year.
Defending champion Andy Murray wasted little time on Centre Court later as he polished off Roberto Bautista Agut of Spain in their third round clash.
Third seed Murray won 6-2 6-3 6-2 and will play Kevin Anderson of South Africa for a place in the quarterfinals Monday.
But sixth seed Tomas Berdych of the Czech Republic went out in a late evening upset, losing in straight sets, 7-6 6-4 7-6 to Marin Cilic of Croatia.