I've been thinking about Kim Clijsters a fair amount these past few days; I think she's going to have a big -- a very big -- 2010. So she's my choice as the most likely player of the year on the women's side; later this week, I'll also choose a potential male PoY for 2010.

My feelings about Clijsters didn't really crystallize until I read and thought about the return of Justine Henin. Yes, these two Belgians are joined at the metaphorical hip, and have been for a long time. And one reason I think Clijsters will do well is because 2010 represents a great opportunity for her finally to escape from Henin's shadow. I'm sure she wouldn't mind at all if she also puts Henin into her own. Payback. It's an itch.

The Clijsters saga, despite all those elements that could be stitched onto a sampler pillow, seems so artfully constructed that Kim or her advisers couldn't possibly have dreamed it up. In 2007, when she "retired" (it's a prettier word than "quit"), she had one Grand Slam title to her credit, and a long history as a talented but woefully choke-prone competitor. She was 1-5 in major finals, and 12-10 against her nemesis, the dynamo Henin. But keep in mind that from 2001 to 2003, Clijsters dominated Henin, including in some major events; from 2003 on, the tables were dramatically turned. The turning point came in Berlin, in 2003, where Henin squeaked out a win, 7-5 in the third. A few weeks later, the Sister of No Mercy surrendered just four games to Clijsters in a brutal Roland Garros final, winning 6-0, 6-4. That opened the floodgates: from that point on, Henin was 8-3 (4-0 in major finals) against Clijsters.

Clijsters also suffered at the hands of Venus Williams, although a few wins late in their rivalry helped Clijsters build the H2H to a respectable 5-6. Champagne Kimmy was less successful against Venus's sister, Serena, who was 7-1 (and 2-0 in majors) against Clijsters at the time the latter took her break from tennis. Clijsters did manage to wave good-bye with a positive H2H against Maria Sharapova, 4-3, although she was 1-1 against Maria in Grand Slam semis. Clijsters was a narrow 8-7 with Amelie Mauresmo, but hey - she owned that other Grand Slam champ, Svetlana Kuznetsova (7-1)! Didn't everyone?

Given all this, you might be inclined to think that Clijsters was totally bummed out when she heard that Justine Henin was following her out of seclusion, but the operative word there is "following." Henin is the one doing the following now, which is a 180-degree shift, and symbolic in a larger sense of where the two women stand in relation to each other. Given the way Clijsters stole the summer headlines in '09, the message seems clear: Clijsters has re-invented herself (that cute little kid of Clijsters is, among other things, a convenient distraction, although Clijsters certainly doesn't see it that way). The problem for Henin is that there was nothing to re-invent; she just faces the challenge of getting back to what she once was. She's burning a different form of emotional fuel.

The other day, in my post at ESPN, I went into the reasons that Henin might have a tougher row to hoe in her comeback than did Clijsters. I wrote that because her game is rooted in finesse and versatility, it may take her a long time to find her timing and turn her on-court decision-making into an instinctive reaction. But there's a little more to it than that. When I compared Clijsters to a four-wheel drive pick-up truck and Henin to a Ferrari, I was also thinking about where the game is, in general, and what it takes to win - on both tours.

Men's tennis has become, over recent years, a much more physical game. Pure power no longer reaps enormous benefits in the form of aces or winners the way it once did; it now pays off in long-haul stamina. Not just the ability to run for a long time, but the ability to maintain racket-head speed, quick-start muscle reactions, consistency of stroke. The relatively new polyester strings have played a part in this evolution; the harder you swing now, the more confident you can feel that the shot will go in. This has had a huge impact on the game (although we've seen that mostly in the men's game - so far).

A racket isn't a very heavy object, but when you have to swing it accurately, with something like full force, for two-and-a-half hours or longer, it can feel like an anvil. This will be an increasingly big factor in the women's game, too - just as serving power and efficiency is a new frontier that the women are finally beginning to explore.

Clijsters is well-positioned to take advantage of these developments, because she's an exceptionally physical athlete. A few weeks ago, Caroline Wozniacki told me (she was talking about her U.S. Open final against Clijsters): "That was the first time I’ve played her. She’s hitting a heavy ball. Every time you play short, she takes another step forward and wants to be the first to attack. She’s a good runner, too, and a fighter. I wouldn’t call it a different level from the other girls, but she was fresh and relaxed. She’s accomplished all she wanted already, so she’s just playing for herself and her family. I could feel she was relaxed and enjoying the game."

With all due respect to Caroline, I'm thinking it might be a different level.

We all love to watch tennis matches, and sometimes we get in too wrapped up in the details of the game - how someone hit the ball on a certain day against a certain opponent. We can learn a lot from that, but there's a forest-and-trees element at play, because so much of what happens in any specific match is determined by form of the day. We get a better understanding of the game if we look at how a player's fundamental profile fits into the gestalt. To me, the game is becoming more and more physical, and Wozniacki's experience puts into perspective the threat Clijsters represents to her peers and rivals.

If you want to read a counter-point, check out the piece Tom Tebbutt wrote for ESPN on this subject. Tom is a tennis aesthete who worships at the altar of Federer, irretrievably in love with "beautiful" tennis. And with Henin back and Roger Federer in command of the men's game until someone says otherwise, fans of pretty tennis are experiencing glory days. I'm not sure how much longer that will be sustainable, though. Last year's men's U.S. Open final was telling to me, in that it represented the first time that someone other than Rafael Nadal was able to play the game on his own terms on a big stage and get the best of Federer. Against Juan Martin del Potro in that final, Federer took his familiar position: Play any way you want; I'll still find a way to beat you. Del Potro responded with: Okay, its power tennis, with the emphasis on physicality.

In that match, Federer was banking on his formidable abilities to transition from defense to offense - to absorb del Potro's most punishing blows and use them roughly the way wise Yoda used The Force in Star Wars. Yoda, of course, was much older than Federer (Yoda was 900-plus years when he died; that's older than Jonas Bjorkman!) and his complexion was considerably greener than that of the olive-skinned Swiss. But in the end, Federer was unable to turn del Potro's power against him, and he spent most of the match futilely chasing rockets. Even when he did catch up with them, they were too hot to handle and fire back.

For different reasons, Clijsters took a similar, Federer-esque attitude into her U.S. Open semifinal with Serena Williams, but she came away with a different result (the match was close enough before the bizarre ending to draw that conclusion, no matter what might have happened at the end in a more conventional scenario). And she was one of the very few women who managed to resist Serena's shoving and pressing and athletic bullying.

!95509212 The first time around, Clijsters suffered some injuries that hampered her effectiveness and probably contributed to her disappointing results in the late stages at some big events. But her game, specifically her physical attributes and abilities, were never in question. Like the lion in the Wizard of Oz, the thing she most needed was a heart. Other players, including Pete Sampras and Martina Navratilova, have faced and conquered a similar shortcoming. There's no reason Clijsters can't do it as well. If she's managed to banish her demons and her smoldering resentment of the way Henin once stole her thunder, she's positioned to flourish.

Now that the Williams sisters are nearing the finish line of their careers and appear to be in some stage of physical decline, Clijsters moves up is an ideal specimen for an increasingly physical game.