The end of the 2013 season was tough on many of the top women, but not on Petra Kvitova. Like Agnieszka Radwanska, she let a golden opportunity slip through her fingers at Wimbledon, and she had bouts with bad health all year. But by fall she had put it behind her and was playing her best tennis of the season. Kvitova finished with a title in Tokyo and semifinal runs in Beijing and Istanbul to end the year ranked a respectable No. 6.

That’s the upside. The downside is that momentum, whether it’s from season to season, week to week, match to match, even game to game, rarely means much when it comes to Kvitova—you really never know what you’re going to get next. But there is a sense right now that her slide, which took her from No. 2 in 2011 to the lower reaches of the Top 10 last year, has been halted. She’s in the mix for major titles, and we know, if everything falls into place, that the 2011 Wimbledon champion can win them.

Ad-In: Kvitova isn’t consistent, but she’s one of the few women who can hit with Serena, Vika, and Maria, and even outhit them on the right day. If her positive attitude and play from late 2013 continues, she should threaten for another major title. If nothing else, she knows she can go the distance: Kvitova won a tour-high 25 of 37 three-set matches in 2013.

Ad-Out: The Czech can avert disaster, but she can also invite it—she always seems a couple of misfires from implosion. After a big 2011, she retreated to the periphery the last two seasons, and that could continue if she loses a few more of those three-setters she loves so much. If you live on the edge, you can fall off any time.

As we approach the new year, we'll take a closer look at what's in store for the past year's top performers. To read more of our 2014 Season Previews, click here.