Serena Williams's Tennis Winning Streak

See update after 2015 Australian Open.

Serena Williams brings a career-best 30-match winning streak into tomorrow's women's singles final of the French Open -- and a 12-match winning streak in head-to-head matches against her opponent tomorrow, Maria Sharapova. Williams presumably will be a heavy favorite to win this Grand Slam event, but even if we just look at what she has accomplished in the last few months of non-Grand Slam tournaments, it's still pretty remarkable.

First, Williams is a power player, with the New York Times quoting multiple experts that her serve is the best ever in the women's game. Yet, her 30-match winning streak has occurred mostly on clay, a surface that slows the ball down. In fact, of Williams's 15 Grand Slam titles to date, only one has come at the French Open (2002), which is played on clay. The other 14 have come at the Australian Open, Wimbledon (All-England), and U.S. Open championships, which are played on faster surfaces.

Second, Williams is currently 31 years old, a seemingly advanced age at which to embark on a career-longest winning streak. The study of baseball statistics ("sabermetrics") has produced "age curves" of players' productivity over time. I was not familiar with age curves for tennis, so I created a rough estimate of them for seven all-time great women's tennis players: Serena and her sister Venus Williams, Margaret Court, Billie Jean King, Chris Evert, Martina Navratilova, and Steffi Graf. You may click on the following graphic to enlarge it.

To arrive at these players' ages at which they won Grand Slam tournaments, I compared their dates of birth to these rough guidelines of when the finals of the four tourneys are held: Australian, early January; French, early June; Wimbledon, early-mid July; and U.S. Open, early September. The Australian Open has switched back-and-forth between December and January, but I used January throughout my analyses. Thus, it's quite possible that I could be off a year on some of these players' ages.

The main finding appears to be that most of the great women's tennis players of the modern era have tended to tail off beginning in their late twenties. Serena, in contrast, had some (relatively) lean years in her mid-twenties (three Grand Slam titles in the five years from ages 22-26), before experiencing a renaissance from ages 27-30 (six titles in four years).

As far as Serena's current 30-match win streak, she is still quite a ways from the top five women's winning streaks (Evert holds the fifth-longest streak at 55 straight wins), let alone the longest women's winning streak of all time, 74 matches by Navratilova. (A list of the longest women's tennis winning streaks, as of March 2012, is available here.)

The way Williams is playing, and with the upcoming switch to grass-court tournaments leading up to Wimbledon, I wouldn't rule out anything for her.