Things seemed to be going according to plan in the early stages of Petra Kvitova’s third-round match with Julia Goerges in Stuttgart on Thursday. Through the first two and a half games, each of these notoriously inconsistent players had shown off, as expected, a few gems and a few flaws. At 1-1, serving into the deuce court, Kvitova threw her toss up for a second serve. The ball seemed to be in the right place above her, her swing looked OK, and her serve landed near the middle of the box. Unfortunately, it was the middle of the ad court box, a meter or so wide of the center service line. It was, by all appearances, going to be one of those days for Kvitova.

But as anyone who has followed Kvitova’s career with an even cursory interest knows, appearances can be deceiving when it comes to the 23-year-old Czech. If you're a gambler, you might try this as your betting system with her: Whatever you think Kvitova is going to do, that means she’s about to do the opposite. Of course, that's not how it worked this time. This time Petra would follow that double-fault with some similarly horrid play through the rest of the first set. With the German playing inspired tennis in front of her home-country fans and on her favorite surface, it looked like an early exit for Kvitova was all but assured.

Naturally, she won the match, and won it going away. Kvitova finished the third set with a volley of cannon-shots winners, and very few errors in between them. The memory of that earlier hacker-level double fault was long gone. She had won her second-straight three-setter—Kvitova often rides the tennis see-saw—and will face second seed Li Na on Friday.

Kvitova has had—can you guess?—and up-and-down season so far. After being upset by Laura Robson in Australia, a Czech journalist warned me that the bottom seemed to be dropping out for Kvitova. What did she do next? She went to Dubai and beat Ana Ivanovic, Agnieszka Radwanska, Caroline Wozniacki, and Sara Errani for the title, then moved on to Doha and played one of the best matches of her career in nearly beating Serena Williams. This was the Kvitova of 2011, the Wimbledon champion who had threatened to take over No. 1, and who was widely believed to be the future of the women’s game.

Still, the Kvitova of 2013 is ranked No. 8, not No. 1, and her results in March and April have been more traditionally mixed. She arrived in Stuttgart trying to forget her biggest disappointment of the year so far, the defeat of her beloved Fed Cup team, the two-time defending champions, at the hands of Italy in the semifinals. Kvitova has always thrived in the team competition; as with many unsteady talents, playing for others seems to focus her, to force her to cut down on the walkabouts. This time, though, she took a stinging straight-set loss to Roberta Vinci on the first day, and the Czechs never recovered.

What’s holding Kvitova back? Why has she turned out, so far, to be a perennial dark horse, rather than the game’s next thoroughbred? Comparing her to another 23-year-old, Victoria Azarenka, is instructive. At the end of 2011, Kvitova beat Vika in a high-quality three-setter to win the WTA Championships. Power won the day that time, and many of us assumed that Kvitova’s strength in that department would continue to win the day. That’s how it had been for the women since the late-90s, when Venus and Serena Williams upped the pace quotient. Women’s Grand Slam champions were inevitably the players who could hit the ball past their opponents from the baseline. I wrote at the time that Kvitova was that type, while Azarenka wasn’t, and that’s why she would struggle to win majors.

I was wrong. What happened instead was a little like what has happened on the men’s side in recent years—speed, even more than power, has become the paramount virtue. Azarenka, like Novak Djokovic, used a mix of offense and defense, hitting and running, to reach No. 1 and win two Australian Opens. A little farther down the ranking, three scramblers, Radwanska, Kerber and Errani, all passed Kvitova in 2012. At the moment, it’s the Williams sisters’ speed, rather than their power, that’s proving to be their most influential advance. (No woman has put the two together the way Serena has.)

Kvitova isn’t merely a ball-basher: The six-footer makes up for her lack of quickness with pretty good anticipation, and she has touch as well. She hit two forehand drop shots for winners against Georges today. It isn’t that she’s streaky, exactly; Kvitova is literally hit and miss, miss and hit. Alternating bombs and misfires from the baseline, she gives both opponents and fans little rhythm to work with. Her matches can feel like anti-narratives (she’s brutal on the Racquet Reaction writer). Stroke-wise, Kvitova has no middle ground; even from well behind the baseline, she’ll try to send a backhand screaming into her opponent’s corner of the court. She goes for winners from everywhere, because she can hit winners from everywhere; unfortunately, she can also make errors from everywhere. You might advise her to dial it back and hit more safe rally shots, except that she’s inconsistent with those as well.

There’s something else, aside from steady strokes, that marks Kvitova as different from the women’s Top 3. Serena, Maria, and Vika all wear masks of competitive defiance—game faces—when they walk on court. They can be intimidating. Kvitova doesn’t. She can look calm, anxious, frustrated, fired up or downright sad, and when she wins a point that she really wants, she lets out a bloodcurdling shriek in Czech. But personally intimidating she isn’t.

Maybe that’s another reason to root for her. Kvitova’s game can be glorious; she has something of the easy power of her countryman, Tomas Berdych. It can also be a train wreck. But if you can get by her maddening style, this shyly friendly small-town native makes for a likable star—or anti-star.

My favorite part of Kvitova’s win today was a conference she had with her coach, David Kotyza. This wasn’t a lecture or a harangue. Instead of standing above her, Kotyza sat on the bench next to Kvitova. While he did most of the talking, she responded, and her facial expressions let you know that she was listening and processing. When it was over and time was called, the two slapped hands; she looked better for the pep talk. And she was: Unlike many women who get a visit from their coach, Kvitova's game improved, and kept improving.

You never know what’s coming next from her.