While watching Serena Williams come from behind at Wimbledon, older sister Venus sat in the front row stifling a yawn.

Nothing to worry about.

Venus was correct – barely. Serena hit a Wimbledon-record 23 aces, held every service game and escaped an upset bid by Zheng Jie, winning 6-7 (5), 6-2, 9-7 in the third round Saturday.

Williams, who erased all six break points she faced, served three times to stay in the match and held each time at love. She was pushed to deuce serving in the final game but closed out the victory with a volley winner, then hopped in glee on the Centre Court grass.

”I just wanted to get through that match,” Williams said. ”The last thing I wanted to do was lose.”

On an eventful day at Wimbledon, unseeded Yaroslava Shvedova swept every point in a set, American Sam Querrey lost the second-longest match ever at Wimbledon, and three-time runner-up Andy Roddick fended off questions about retirement after being eliminated.

The 5-foot-4 1/2 Zheng, seeded 25th, played with little flash but plenty of consistency against Williams, committing just 17 unforced errors. She hung in the match despite hitting only one ace.

Venus Williams – a five-time champion who lost in the first round – may not have been concerned, but Serena looked plenty worried. She rocketed a return to break for an 8-7 lead in the final set, then showed how much she wanted to win, throwing back her head and letting out a long scream.

Williams has been stalled at 13 Grand Slam titles since winning Wimbledon for the fourth time in 2010, and dealt with a series of health issues in 2010-11.

Her next opponent will be Shvedova, who won all 24 points in the first set – a so-called ”golden set” – and beat French Open runner-up Sara Errani 6-0, 6-4. It’s the first known golden set by a woman in the Open era, the International Tennis Federation said, and the BBC showed a highlight package of all 24 points.

Williams will face Shvedova on Monday.

”Hopefully I’ll be able to win a point in the set,” Williams said. ”That will be my first goal, and then I’ll go from there.”

Defending champion Petra Kvitova, No. 2-ranked Victoria Azarenka and former French Open champions Ana Ivanovic and Francesca Schiavone also reached the fourth round.

Lukas Rosol, who stunned two-time champion Rafael Nadal in the second round, flopped in his follow-up, losing to No. 27-seeded Philipp Kohlschreiber 6-2, 6-3, 7-6 (6).

”I knew that this can happen,” said Rosol, a Czech ranked 100th. ”I was thinking only just to don’t sleep and open eyes again and play good tennis.”

Americans Mardy Fish and Brian Baker made the round of 16, but not Roddick. He failed to convert two set points in the second set and lost to No. 7-seeded David Ferrer 2-6, 7-6 (8), 6-4, 6-3.

Roddick, whose ranking is in decline at age 29, wouldn’t say whether he thinks he’ll be back for Wimbledon next year.

”If I don’t have a definitive answer in my own mind, it’s going to be tough for me to articulate a definitive answer to you,” he said.

Fish, playing in his first tournament since undergoing a procedure on his heart in May, beat David Goffin 6-3, 7-6 (6), 7-6 (6). Baker, an American mounting a career comeback from reconstructive elbow surgery, continued his surprising run by beating Benoit Paire 6-4, 4-6, 6-1, 6-3.

”It is crazy, kind of, what’s going on,” said Baker, ranked 126th. ”I’m still trying to stay focused on the task at hand and not get too wrapped around it. Because once you do that, I think it’s tough to be able to play your best.”

The unseeded Querrey lost to No. 16 Marin Cilic in a 5 1/2-hour marathon, 7-6 (6), 6-4, 6-7 (2), 6-7 (3), 17-15. No. 5 Jo-Wilfried Tsonga swept Lukas Lacko 6-4, 6-3, 6-3 and next faces Fish. No. 4 Andy Murray’s four-set victory over Marcos Baghdatis ended at 11:02 p.m. to end the day.

On a sunny, windy afternoon, the retractable Centre Court roof was open after being closed all day Friday, and the breeze that had Williams’ skirt flapping might have contributed to her slow start. She struggled with her returns, and several times shanked serves by Zheng that barely reached 100 mph.

Williams didn’t have a break-point chance in the first set, and every point Zheng won in the tiebreaker came on an error by her opponent, including two mishit returns.

”I thought, `Serena, just relax and be calm,”’ Williams said. ”I felt good. I never felt like I was going to lose this match.”

Williams briefly locked on Zheng’s serve in the second set, sweeping the final 13 points to even the match.

In the last set, Williams overcame a love-40 deficit to hold for 2-all. Two games later, when she bounced a kick second serve over her opponent’s head for an ace, Zheng managed a laugh.

Later in the set Williams won 14 consecutive service points, including three aces in one game to reach 7-all. She held 18 times and lost only 18 of 98 service points.

”It’s a tough match, because she has big serve,” Zheng said. ”It’s very difficult against her on the grass court.”