The WTA Finals—the season-ending championship of women's tennis—begins on Monday, October 20 in Singapore. Throughout eight days, we'll take a closer look at the seasons put forth so far by the eight singles competitors.

Serena Williams has had a year filled with dispiriting lows—and one enormous high. She got off on the wrong Grand Slam foot at the Australian Open (losing to Ana Ivanovic in the fourth round) but rebounded to win her 59th WTA title in Miami. Garbine Muguruza eliminated her from the French Open in the second round.

When Williams was upset for the second time this year by Alize Cornet—this time at Wimbledon—the WTA theme of the year became obvious: Would Williams play an entire year winning large combined events like Miami, and failing to win a single major? She answered at the U.S. Open with a resounding, “Not in this lifetime, bub!”

At the U.S. Open, Serena battled self-doubt, critics and blazing heat to win her 18th singles title.

It’s one thing to be upset by talented if not fully realized Alize Cornet in Dubai, quite another to lose to her again—at Wimbledon.

Quite honestly, nothing at all. Serena has been playing with house money for years now. Her superiority is such that Maria Sharapova, the No. 2 player in the world—and a woman who also has a career Grand Slam—hasn’t beaten her since 2004 (Serena leads 16-2). If Serena's knee improves enough to allow her to play at full strength, she’ll be merely padding an already over-stuffed resume with a win.

WTA Finals Previews

Sunday, October 12: Agnieszka Radwanska
Monday, October 13: Ana Ivanovic
Tuesday, October 14: Caroline Wozniacki
Wednesday, October 15: Eugenie Bouchard
Thursday, October 16: Maria Sharapova
Friday, October 17: Petra Kvitova
Saturday, October 18: Serena Williams
Sunday, October 19: Simona Halep