Maria Sharapova Maria Sharapova of Russia celebrates winning the second set tie break against Alexandra Dulgheru of Romania during the Sony Ericsson Open at Crandon Park Tennis Center on March 29, 2011 in Key Biscayne, Florida.

Sharapova vs. Petkovic:  Entrenched in the top 10 for the first time since February 2009, the Russian aims to dispel the memories of two previous losses this year with a single mighty blow.  Eager to counterbalance a lackluster performance in her previous semifinal at Indian Wells, Sharapova would relish the opportunity to atone for an equally mediocre display against Petkovic.  Overwhelmed by Maria in Cincinnati, the German turned the tables in stunning fashion at the Australian Open, where she never faced a break point until after she held a match point.  Petkovic seeks her third consecutive victory over a #1 after grinding past Wozniacki and Jankovic in two matches that featured a multitude of deuce games and break points, testing the 21st seed’s tenacity.  In her excruciating, exhausting, but ultimately exhilarating 209-minute quarterfinal triumph against Dulgheru, Sharapova demonstrated even greater fortitude by twice escaping from within two points of defeat despite 17 double faults and 76 unforced errors.  Perhaps the only player in the WTA who could survive such a statistical catastrophe, the three-time major champion overcame further adversity when she twisted her ankle during the quarterfinal’s penultimate moments.  All too familiar with aching joints, the two-time Miami finalist must quell her anxiety over this injury as she attempts to recover from the longest match of her career.

Brilliant in this tournament until near-disaster on Tuesday, Sharapova must recapitulate her magnificent Monday form in order to halt Petkovic’s accelerating momentum.  If her groundstrokes yield the same deluge of unforced errors as on Tuesday, this semifinal will not end any more brightly than the last.  Across the net, the German must alter her strategy against an opponent who diverges so radically from the two counterpunchers.  Targeting her foe’s forehand and disrupting her timing with heavy spin, Petkovic hopes to prevent Sharapova from planting herself inside the baseline to target lines and corners at her leisure.

Zvonareva vs. Azarenka:  Pinning Clijsters behind the baseline with relentless groundstroke depth, the 2009 Miami champion delivered one of her most complete performances against an elite opponent since winning this title two years ago.  Under pressure from the Belgian’s late surge, Azarenka constructed a startlingly thoughtful point at 5-3, 30-30 just after an edgy double fault.  The eighth seed patiently maneuvered the defending champion around the court and withstood the rally’s mounting tension better than her more experienced opponent, who finally conceded a frustrated forehand error.  Against the versatile Zvonareva, she will need to control her aggression just as calmly in order to reverse an odd rivalry in which the advantage currently lies with the Russian.  Following two dismal losses to Vika early last year, the world #3 reversed that slide after her Wimbledon breakthrough with two second-half wins.  Sharing balanced, penetrating groundstrokes, Vika and Vera have honed extremely consistent games with few clear flaws albeit few overpowering weapons.  Notorious for emotional implosions, both have maintained their composure at crucial junctures en route to this semifinal.

Often fallible on serve, Zvonareva struck an ace to save a set point against Radwanska in her quarterfinal and has welcomed unexpected contributions from that shot throughout her last few tournaments after a shaky serving start to the season.  Among the few flaws in Azarenka’s performance this week, meanwhile, was a delivery that donated seven double faults and rarely represented more than a point-starting shot.    Thus, the contrast in their serving could play a crucial role in the outcome, as could Zvonareva’s superior experience on these stages.  Surely relieved to avoid Clijsters, the Russian now dons the mantle of tournament favorite.  Can her nerves and a fearless foe unfasten it?

Federer vs. Simon:  Among the few players outside the top 20 with repeated success against Roger, the Frenchman seeks to build upon his two 2008 triumphs over the Swiss master.  Twice surmounting one-set deficits in this tournament, Simon has produced his first sustained surge at a significant tournament since injuries derailed him a year ago.  Meanwhile, Federer has glided effortlessly past a sequence of anonymous opponents, none of whom enjoyed either the power of the consistency to unsettle him.  Clearly unsettled by Simon, in contrast, the third seed squandered a two-set lead against him at the Australian Open before reasserting his supremacy in the final set.  Although Federer possesses weapons superior to those of the Frenchman in most areas, the latter’s two-handed backhand trumps the Swiss star’s elegant but unreliable one-hander.  As the 16-time major champion ages, moreover, his decreasing consistency also renders him increasingly vulnerable to an indefatigable retriever like Simon.  Darting along the baseline, Gilles forces Roger to win points more than once and often to attempt strokes too aggressive for his court positioning.  First-serve percentage should prove essential for both players, allowing Federer to hold swiftly while shielding Simon’s benign second serve from exposure.  Unlikely to outlast the Frenchman from the baseline, the Swiss star should capitalize upon his forecourt abilities whenever possible to take time away from an opponent who showcases his counterpunching skills to greatest effect on slow hard courts like these.

Nadal vs. Berdych:   Four and a half years ago in Madrid, a budding Berdych dispatched Rafa before his home crowd and then put his finger to his lips in a gesture of disdain towards the Spanish fans.  Nineteen sets later, he has yet to win another set from Nadal, who terminated the most impressive fortnight of the Czech’s career with an emphatic victory in last year’s Wimbledon final.  From clay courts and outdoor hard courts to grass and indoor hard courts, Berdych has found no refuge from the world #1 on any surface.  Outside the context of their Madrid clash, one can find little clear explanation for Nadal’s uncanny dominance over a rival with more than adequate weapons to threaten him on both serve and forehand.  But Berdych does lack one trait shared by Djokovic, Murray, Soderling, Del Potro, and most of the players who repeatedly have troubled Rafa:  a backhand that can equal his forehand in percussive assertiveness.  Whereas his recurrent nemeses subject him to constant pressure from both groundstrokes, Nadal finds respite in rallies by targeting the Berdych two-hander.  Also separating the Czech from that group is his unsteady focus, which resulted in an unnecessarily extended opener here and nearly a loss to Florian Mayer a round ago.  Against the fiercest competitor in the ATP, that trait proves especially damaging.  A runner-up in Miami last year, Berdych stunned Federer, Verdasco, and Soderling consecutively during the fortnight.  Can he rekindle those memories by bursting free from the vise in which Rafa grips him?

Rafael Nadal - Sony Ericsson Open