Serena Williams powered down a record 23 aces as she fought back from one set down to edge past China's Jie Zheng in an epic encounter on Centre Court.
Williams previously held a 5-0 win-loss record over Zheng, but the 25th seed produced some excellent tennis today to make the American look ordinary at times on the Centre Court where she has previously won four Wimbledon titles.
A series of bruising serves prevented Williams from following sister Venus out of the tournament as the 30-year-old clinched a 6-7 (7/5) 6-2 9-7 win.
The 23 aces Williams served was confirmed as a new record for a women's match at SW19. Williams set the previous record of 20 during her semi-final win over Elena Dementieva in 2009.
Williams, who beat Zheng in the last four here in 2008, was impressed with the performance of her 28-year-old opponent.
"She played unbelievably well," said Williams, who faces Sara Errani's conqueror Yaroslava Shvedova in round four.
"I kept fighting in that third set. If I was going to go out I wanted to go out fighting.
"It was good to go through. I needed a tough match like that."
Williams wasted little time or energy in blasting past Melinda Czink on Centre two days ago.
But Zheng made the American aware that she would provide a much sterner test.
Zheng had her opponent racing to all corners of the court in the opening exchanges and earned three break points in the third game after Williams slipped on the baseline.
Williams saved the first with an ace and after two errors from the Chinese, the four-time champion powered down two more aces, the second a 119mph rocket, to hold.
Williams was then put off by the breeze in the first-set tie-break as she aborted her ball toss on the first point. The American also lost focus to send a simple backhand long.
Williams let out a typically forceful scream of "Come on!" as she broke back to level at 5-5 in the breaker, but Zheng was unmoved and soon clinched the set when forcing the American to hit a backhand wide.
Any hopes Williams had of an immediate break in the second set were dashed when Zheng held to love, but the American inflicted damage in the fifth game when her opponent ploughed the ball into the net at 30-40.
Zheng's fight seemed to have evaporated as she was broken to love in the seventh and Williams served out to level the match.
The deciding set was tense but peppered with Williams aces.
Zheng showed nerves of steel to hold to love and lead 5-4.
Both players refused to back down and the set moved to 7-7, at which stage Williams earned her first break point of the set.
Zheng survived that but gave Williams another opportunity moments later, and this time the chance was taken as the underdog fired long after a powerful Williams forehand.
Despite an early double fault when serving at 8-7, Williams engineered two match points at 40-15.
Zheng showed she still had fight in her by returning two sharp backhands to force deuce.
But when it arrived the sixth seed did not squander a third match point, and she leapt up with clenched fists, clearly delighted to have avoided a shock defeat.
