London: Wimbledon's grass claimed its most notable victim so far when the women's world No. 2 Li Na exited the tournament and the lush lawns almost did for top men's seed Novak Djokovic as he took an agonising tumble.
Australian Open champion Li came up against fired-up Czech Barbara Zahlavova Strycova, who has never before advanced beyond the third round of a Grand Slam.
The pair fought a tight two hours and 19 minutes duel that could have gone either way, but the determined Czech held firmer in two tie-breaks to win 7-6 (5), 7-6 (5).
China's Li, the second seed, said she felt she had not had enough practice on grass coming in to the tournament.
"It's not only about technique. I think sometimes I don't know how to play the point, especially in the important moment. I think today I made a lot of mistakes."
Djokovic was cantering towards a regulation victory against Frenchman Gilles Simon on Centre Court when, with the score at 6-4, 6-2, 3-2, he slipped before flinging himself at a forehand. He fell heavily, appearing to jar his elbow, and was left wincing in pain as he rolled on the turf clutching his shoulder.
His coach Boris Becker, so demonstrative as a player, was a picture of calm inscrutability in the courtside box until Djokovic's fall. The German three-time champion stood up, leaned forward and watched anxiously as his charge received treatment.
After some shoulder manipulation by his chair, the Serb resumed as if nothing had happened and finished off Simon 6-4, 6-2, 6-4 with a characteristically athletic airborne smash.
"It was a sharp pain when I fell, an awkward fall," the six-time Grand Slam champion said. "I was just hoping there is nothing going on with the joint. Luckily there is no damage and I could play."
Djokovic will now meet France's Jo-Wilfried Tsonga in Monday's fourth round. Women's third seed Simona Halep suffered a less spectacular scare, dropping a set against unheralded Ukrainian Lesia Tsurenko in a delayed second-round match.
Halep, who has vaulted up the rankings over the past year and reached the French Open final this month, eventually saw off the world No.170 6-3, 4-6, 6-4, but not before throwing away two match points as she struggled with her nerves.
"You know, on grass it is not easy. Every match is difficult. You never know who will win or who will lose because of the court," Halep said.
Battling Australian Leyton Hewitt bowed out of the tournament he won in 2002, but not before giving 15th seed Jerzy Janowicz a thorough workout in a second-round match held over from Thursday.
Pole Janowicz, who reached the semifinals last year, prevailed 7-5, 6-4, 6-7 (7), 4-6, 6-3 and will meet Spaniard Tommy Robredo in the third round. It was Hewitt's 42nd five-set Grand Slam match and gave the 33-year-old the record for most five-setters since the start of the professional era in 1968.
Battle of former champs Meanwhile, Petra Kvitova fought back to defeat Venus Williams 5-7, 7-6 (7/2), 7-5 in a titanic battle of the former champions.
Kvitova, the 2011 winner, and five-time champion Venus treated Centre Court fans to a high-quality third round encounter lasting two and a half hours before the Czech sixth seed finally prevailed, extending her impressive record against the 34-year-old American to four wins from their five encounters.
The 24-year-old, who has reached at least the quarterfinals in each of her last four visits to Wimbledon, will play Chinese world No. 61 Peng Shuai for a place in the last eight.
Venus's defeat means the seven-time Grand Slam winner has failed to reach the last 16 at a major since Wimbledon in 2011.