WTA Championships Day 1 thoughts

Sam Stosur (pictured) defeated Maria Sharapova for the first time in 10 tries. (Reuters)

ISTANBUL -- Observations from the first day of the WTA Championships, where Sam Stosur pulled off a surprise, top-seeded Caroline Wozniacki battled and the favorite, Petra Kvitova, overcame her nerves.

• Streaks were made to be broken: Stosur likes a challenge -- that's been one of the big WTA themes in 2011. She's spent much of this year losing when she's expected to win and winning when she's expected to lose. Such was the case on Tuesday, when she beat Maria Sharapova for the first time in 10 career meetings. The Aussie's 6-1, 7-5 victory seemed to be a redux of her U.S. Open final against Serena Williams, where Stosur cruised in the first set and fought off a reinvigorated champion in the second set to secure a milestone win.

In the past, Sharapova has been able to handle, if not take advantage of, Stosur's heavy kick serve, using her height to step in on her returns to hit clean winners or seize early control of a point. That wasn't the case here, as Stosur mixed up her serves and did not rely on the kick serve to the point of predictability. Most surprising was the noticeable improvement in Stosur's movement and her backhand. Much as she did against Williams, Stosur kept herself in rallies with her legs. She made the rusty Russian -- who was playing for the first time since injuring her ankle nearly a month ago -- hit the extra shot, and the lack of match play for Sharapova definitely showed.

"It's obviously tough to come back after a month and compete at this level," Sharapova said. "I think she was much more explosive than I was, and she used her slice really well today and it stayed quite low in the court. She just played really solid and really well and moved extremely well around the court and made me hit another ball.  And maybe I just went for a little too much and wasn't as consistent as I should have been."

The look of relief on Stosur's face after match point said it all: This was a big one for her. Not only did she play her best match since the U.S. Open, but Stosur also finally broke through the mental block she admitted she had against Sharapova, and she did so without being able to rely on her big forehand to hit winners on the slow indoor surface.

"With the conditions and the court, it's not conducive to doing that," Stosur said. "That's probably why I am probably so pleased with that win is because I couldn't use my best weapons out there but managed to do other things with them and got a straight‑sets win over somebody I've never beaten before. Yeah, to win without using your best strengths is a big bonus."

Stosur won't have much time to enjoy the victory. She's first on court Wednesday against another player she's never beaten or taken a set from, Victoria Azarenka, who leads the head-to-head series 4-0.

"Hopefully tonight is going to be a good omen that things are turning around in my favor against players that I've struggled with," Stosur said.

• The fighter: Wozniacki's face may top glamorous magazines and advertisements all over the globe, but it's her ability to win ugly that has helped her maintain the No. 1 ranking for almost a year. In her long tussle against Agnieszka Radwanska, which she won 5-7, 6-2, 6-4, the Dane reminded us that when her back is against the wall, she almost always finds a way to win.

While the match was infuriating to watch (how many simple forays to the net ended in calamity?) and both players showed their nerves (Wozniacki blew three set points in the first), it was also entertaining. Radwanska's aggression and willingness to finish off points at the net seemed to goad her good friend into trying to do the same. Wozniacki, usually unmovable from the baseline, didn't hesitate to venture forward, and while her success varied, the intent was right and encouraging. There's no reason she can't develop that part of her game to make things easier on herself.

• Kvitova's refreshing humility: Kvitova is the oddsmakers' favorite to win this event, but don't tell her that. She may be a Grand Slam champion who has performed well on a big stage, but it's easy to see that she hasn't bought into her own hype quite yet. She admitted to being wracked with nerves before her match against Vera Zvonareva, and those nerves seem to take hold during the match as well.

Serving up 6-2, 4-1, Kvitova followed an approach shot to the net only to stop dead in her tracks as Zvonareva hit a perfect lob that landed inches from the baseline. The shot seemed to rattle Kvitova, who shot a look over to her coach and proceeded to miss a forehand badly and then double-fault the break away. Next thing you know, the second set is level at 4-4 and Kvitova is slumping her shoulders as though she's already lost the match. You can't blame her mind for going there. She did, after all, blow a 5-1 lead to Zvonareva a few weeks ago to lose 7-5, 6-0 in Tokyo.

Kvitova finally shook off her nerves to break for 5-4 and then serve out the match, improving to 15-0 indoors this year. But these lapses serve as a reminder that as much hype as Kvitova receives (and deserves), she's still very much a work in progress and most of that work has to do with her brain. Humility can be both a gift and a curse, and while Kvitova may never get to the point where she truly believes she's a top dog, it would do her well to at least become comfortable in that role. Maybe that will ease her nerves.

• Slow hand: The sluggish, low-bouncing Rebound Ace court surface was a hot topic of conversation on Day 1. Wozniacki described it as "sticky -- you feel it in your legs." Radwanska said it was "weird" and noted that it was difficult to terminate rallies, which inspired my favorite press conference moment of the day. Sharapova, when told about Radwanska's comments, responded, "I think if there is any court that Radwanska likes, that's slow. So I'm not sure what the complaint is about." Maybe you had to be there, but Sharapova's confused expression sold the quip.

But it is a slower court and the players are taking note. The big hitters who won, Kvitova and Stosur, were intentionally hitting with more spin as opposed to trying for winners. And with Radwanska unable to finish off points unless at the net, she found herself embroiled in a two-and-a-half-hour affair with Wozniacki. It will be interesting to see if the surface continues to influence the matches as the week progresses.

Fine start for Turkey