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.