Pressure may have been a privilege for Billie Jean King, but for China's Li Na it is an inescapable fact of life.  Long burdened with the towering  expectations of her compatriots, Li nevertheless has brilliantly represented Chinese tennis on the biggest stages in the sport.  Not just personal achivements, her successes have proved vital in sparking a wave of talented compatriots to follow in her footsteps--an influence that few players can claim.  Consequently, Li is the subject of our second player profile, in which we will recall five highlights and five lowlights of her career, discuss three strengths and three weaknesses in her game, and conclude with a preview of what her future may hold.Highlights:5)  2006 Wimbledon:  Li announced herself to the international tennis audience on the biggest stage of all, overcoming 2004 US Open champion Kuznetsova and Nicole Vaidisova (then a formidable threat on grass) en route to the quarterfinals.  Her performance at the All England Club made her the first Chinese player ever to reach the final eight in a Slam draw and, more tellingly, illustrated her ability to threaten the WTA elite under the most pressure-filled situations.4)  2008 Gold Coast:  After a lengthy injury absence in 2007, few tennis aficionados expected Li to rebound immediately by seizing the most important title of her career so far.  In this Australian Open warm-up tournament, she once again defeated the still-dangerous Vaidisova before scoring a gritty three-set win over the already promising Azarenka in the final.  Watching her steadily wrest control of the match away from the Minx from Minsk, we were struck by her mental fortitude and composure on key points. 3)  2007 Indian Wells / Miami:  Although her high-risk game doesn't naturally suit the California desert's ultra-slow hard courts, Li slashed her way past consummate counterpunchers Jankovic and Zvonareva.  In the semifinals, she split two tightly contested sets with eventual champion Hantuchova before fading in the final set.  Just a fortnight later, she ambushed Clijsters in Miami with the bold shot-making panache that has defined her style.  These glittering results diverged from a trend in her career, which has witnessed oscillations between stunning success and deep disappointment.  In these consecutive major events, Li hinted at the dominant player that she could become; it's difficult to determine how her year would have developed had she not missed the entire second half with injury.2)  2010 Australian Open:  Not only did Li reach a Slam semifinal and penetrate the top 10 for the first time in her career, but she accomplished these longtime goals in dramatic fashion by upsetting Wozniacki and Venus.  After relentlessly eroding the Dane's dogged defenses, she looked uncharacteristically perplexed during the first set and a half of her encounter with the seven-time Slam champion.  When Venus served for what appeared to be a routine quarterfinal, however, Li lofted two exquisitely executed lobs and capitalized on the sudden momentum shift.  Failing to serve out the match at the first opportunity in the final set, she maintained her steely focus, broke the American again, and slammed the door in style with a pair of flamboyant forehands. If she had eked out the two tiebreaks against Serena in a fiercely contested semifinal, we would have backed her to win the Melbourne title.1)  2008 Olympics:  Although many observers might have considered Li's semifinal (bronze-medal match) run here less significant than her Australian achievement, we placed it at the head of this list because of the immense pressure on her to excel before her home audience in what they consider the world's premier sporting event.  Most WTA players would have crumpled under the weight of the occasion, but instead Li rose above all expectations to overcome Kuznetsova and Venus.  More than just another highlight on her resume, this performance at the Beijing Olympics provided inspiration for a future generation of Chinese tennis players--a contribution to her sport and her nation that one can't easily quantify.Lowlights:5)  2006 Estoril:  After splitting two extremely tight sets with her charming but feisty compatriot Zheng Jie, Li found herself forced to retire from the final before the third set.  The physical rigors of her uncompromising style not only cost her a title but portended numerous injury-caused absences in the future.4)  2008 Stuttgart:  Having toppled the newly crowned US Open champion Serena Williams in this fall indoor hard event (since moved to the spring clay season), Li failed to capitalize on her momentum and fell meekly to Petrova one round later.  Throughout her career, she has repeatedly struggled to transform significant upsets into titles or deep tournament runs, a product of the inconsistency that we discuss below.3)  2009 Birmingham:  In the semifinals of this pre-Wimbledon grass court event, Li defeated Sharapova for the first time in her career after a series of frustrating losses to the Russian in key tournaments (see the next entry).  As in Stuttgart, though, she proved unable to translate the momentum into a title, losing a highly winnable match to the untested Slovak Magdalena Rybarikova, who still has yet to emerge as a serious force in the WTA.  In order to fulfill her vast potential, Li will need to find a way to regularly win the matches that she ought to win. 2)  2008 US Open:  One might have expected that the flamboyant Li would rise to the occasion against the ever-frail Dementieva on Arthur Ashe Stadium, the world's largest tennis venue.  Moreover, she had just captivated international audiences with her Olympics breakthrough (chronicled above); we picked her to pull off what would have been a noteworthy yet not shocking upset.  Instead, she fell on her sword in a cascade of ugly unforced errors, either unable or unwilling to modulate her natural aggression.  This section of the draw had opened up considerably, which only underscored the squandered opportunity here.1)  2009 French Open:  Many readers may be surprised to find a fourth-round Slam showing atop this list, but our choice stems from the context here.  Despite losing the first set to Sharapova, she had rebounded to win 10 of the next 12 games from a distinctly rusty Maria, a surge that propelled her to a 4-2 third-set lead.  With the match on her racket and an increasingly fatigued opponent across the net, she let the Russian find her footing, take over the rallies, and reel off the next four games.  Considering that the rest of her half included the unimposing Cibulkova, the still-raw Azarenka, and the mentally tottering Safina, Li certainly could have fought her way into the French Open final had she closed out the match.  And, as we know well, anything can happen in a Slam final.Strengths:1)  Backhand.  Crisp and efficient with her technique on this stroke, Li can direct it with conviction towards either sideline or corner.  Even when she struggles with the rest of her game, her backhand rarely deserts her for extended periods.  During her matches against Sharapova, she prevailed several times in protracted backhand-to-backhand rallies, no easy feat for opponents confronting the Russian's colossal two-hander.  Li moves extremely well towards that side of the court (better than towards her forehand), so her superior footwork and balance allow her to lean into the shot and generate additional pace.2)  Self-belief.  Beneath her steely facade lies a resilient confidence in her abilities, without which she could not have scored her eye-opening wins over virtually every marquee WTA player in the last decade.  Whereas some opponents walk onto court with eyes glazed in the acceptance of inevitable defeat, Li approaches even her most daunting matches with a predatorial gleam in her eye.  This self-belief matches the fearless aggression in her game; rather than retreat into passivity after unforced errors as do so many of her peers, Li fires her weapons with redoubled determination.3)  Imagination.  During her rallies with Venus in Melbourne, Li consistently kept the American off balance with ingeniously angled groundstrokes that opened up the court in unexpected ways.  Even when her opponent appeared to have firmly seized the upper hand, she often delivered a crafty riposte that enabled her to transition from defense to offense.  Her run at the Olympics also showcased her talent for hitting balls from anywhere on the court to anywhere else; when Li settles into a shot-making rhythm and displays her ability to redirect the ball, few players are more breathtaking to behold.  Well equipped to resist raw power, even expert counterpunchers such as Jankovic and Wozniacki have struggled to weather this hurricane of unbridled creativity.Weaknesses:1)  Inconsistency.  On both macrocosmic and microcosmic levels, Li struggles to maintain momentum after spectacular stretches of play.  She often follows an excellent result with a lackluster performance, or a lengthy sequence of winners with an equally lengthy sequence of errors.  In part, her failure to capitalize on long-term momentum stems from the numerous injuries that have derailed her at inconvenient stages and for extended periods.  The short-term momentum, however, is an issue that she must address in order to prevent opponents from finding new life, which needlessly prolongs early-round matches even if it doesn't necessarily reverse the outcome.2)  Finishing points.  Li's laudable aggressive instincts sometimes boil over the top, inspiring her to attempt a shot closer to the line or more jaggedly angled than would suffice to win the point.  If the court lies open and her opponent is marooned outside the doubles alley, there's no need to nibble at the opposite sideline.  When her game is a fraction off, those picture-perfect winners turn into ghastly, often costly miscues--effectively donations.  We'd like to see Li enhance her net skills, which would not only decrease the opponent's reaction time but enable her to create angles more safely.  Nevertheless, we have to admit that her flair for (melo)dramatic shot-making provides marvelous entertainment, whether for better or for worse.  ;)3)  Stubbornness.  A product of her self-belief, this trait surfaces when Li misses the same shot (and/or the same line) several points in a row.  We're not suggesting that offense-minded players should retreat from natural aggression into a tentative Plan B; there's a reason why Plan B is Plan B and not Plan A.  Neither would we suggest that Li and others play to their opponents' weaknesses rather than to their own strengths.  But a player with multiple weapons should consider trying a different shot or form of aggression if one of her weapons doesn't seem to be clicking at a given moment (e.g., trading a down-the-line forehand for a crosscourt forehand).  Recap: If Li can stay healthy over the next few years, she has a legitimate chance to win a Slam or at least reach a final.  As she has amply demonstrated, she can overcome anyone on any occasion.  As she has equally amply demonstrated, she can lose to anyone on any occasion.  Although thrilling for fans, this unpredictability could cost her over the course of two weeks and seven matches against a variety of playing styles.  However, a little help from the draw and a timely burst of momentum could carry her all the way, especially in this uncertain period in women's tennis.  As we mentioned above, she might well have won the Australian Open this year had she eked out just a few more points against Serena.We suspect that Li's best tennis still lies ahead, and that she will capture at least one top-level title (probably not a major, but a Premier event).  If you think that we're overly optimistic, feel free to tell us so.  But be careful before you underestimate Li Na.***Hope that you enjoyed this second player profile.  Our third edition will feature Russian ATP star Mikhail Youzhny.  Meanwhile, coming up this weekend is the inaugural edition of "(TW)2."  Rather than provide further explanation, we'll let you guess what that abbreviation might signify over the next few days!  :)