More than 20 percent of Williams' aces in the tournament came in that one match; however, it's a safe bet that Williams did not enter that match thinking she would need to hit an inordinate amount of aces to win.
However, IBM Insights -- which tracks data from Grand Slams -- indicated that was, in fact, one key for Serena against Zheng if she wanted to improve her likelihood of winning.
IBM Insights is an algorithm that:
• Identifies what a player can do to increase the likelihood of winning.
• Collects and churns out information based on Grand Slam data over the past seven years.
• Analyzes head-to-head history and matches against "similar" opponents.
• Takes court surface into consideration
This is not meant to determine who will win a given match, but rather what a player can do in order to increase the likelihood of winning a set.
There are three Insights that can be tracked on ESPN.com's CourtCast. At Wimbledon, men who hit all three of their Insights (without their opponent hitting one of theirs) went on to win the set 93 percent of the time. Women won sets 97 percent of the time under such circumstances.
Against Zheng, one of Serena's Insights was to win more than 13 percent of her first-serve points with an ace. When Serena reached that percentage in previous Grand Slam matches against similar players like Zheng, she went on to win the set 94 percent of the time.
Williams lost the first set in a tiebreaker, but more than exceeded her Insight by winning 36.3 percent (8-22) of her first-serve points with an ace. In the second set, which Williams won 6-2, 26.7 percent of her first-serve points (4-15) were won with an ace.
Serena won the final set, 9-7, thanks in large part to the record day she had serving. Almost 40 percent of her first-serve points (37.9) were won with an ace (11-29).
On Tuesday, Williams will play her first-round match against fellow American Coco Vandeweghe. On paper, Williams will be a heavy favorite. And since her serve is such a vital part of her game, you can bet that one of Serena's keys will focus on her service game.