If the weather permits, a diverse sextet of singles matches awaits on the first day of the women’s quarterfinals and the concluding day of the fourth round for the men.

Azarenka vs. Stosur:  Sweeping her five previous meetings with the defending champion in straight sets, the world #1 crushed her in a Premier Five final this year at Doha for the third of four consecutive titles won by Azarenka during her torrid start to 2012.  In that match and others, Vika has reaped rewards by pounding her vicious backhand into Sam’s own two-hander and either moving her opponent out of position or drawing an unforced error from that weaker wing.  For her part, Stosur has tried with much less success to move the Belarussian off the court with a kick serve that sets up her first forehand, the combination upon which she has built her ascent to the top 10.  One of the WTA’s keenest returners, Azarenka not only has denied the Australian many free points on her serve but has retrieved it with sufficient depth to start plenty of rallies in neutral mode.  Her superior athleticism, groundstroke symmetry, and technique offer her substantial advantages from that position.  En route to her first US Open quarterfinal, Vika has thrashed opponents more resoundingly than any of her rivals, conceding just ten games in four matches.  Although Stosur certainly should fare better than those previous victims, perhaps winning a set from Azarenka for the first time, she likely will lack the confidence to halt her futility against her.  Nevertheless, she also has reached this stage in straight sets, and the memories of last year’s title surge should inspire her to an effort worthy of a reigning champion.

Sharapova vs. Bartoli:  Notably similar to the non-rivalry between the first pair of quarterfinalists is the non-rivalry between this second pair.  In each of four straight-sets victories, Sharapova has lost no more than five games to a Frenchwoman who, according to her father, admitted that the Russian intimidates her.  Beyond the fear factor, the 2006 champion simply matches up exceptionally well to Bartoli’s game.  While her sharply angled wide serves into both boxes can exploit the double-fister’s short wingspan, her explosive return can devastate the latter’s modest second serves.  But Sharapova must beware of her opponent’s second-serve return, which has unleashed swarms of outright winners this tournament.  In addition to aiming for a high first-serve percentage, she will want to move forward to finish points, since Bartoli moves deceptively well along the baseline.  Against Kvitova, the 11th seed stayed in rallies despite the Czech’s overwhelming groundstroke power, in part because the latter rarely stepped into the court when she created an opening.  Since neither woman relies on versatility or subtlety, expect a series of short, staccato points in which each woman casts caution to the winds and swings for the lines before her foe can pounce.  Whereas Bartoli looked sharper than Sharapova in the last round, the Russian looked superior during the tournament overall.

Wawrinka vs. Djokovic:  Likely not the last Swiss whom the Serb will meet this fortnight, Federer’s understudy eyes his second US Open quarterfinal after his best result at a major in 2012.  To achieve that feat, however, Wawrinka would need to solve a man against whom challengers have clawed desperately to win not sets but mere games.  Having won nine consecutive meetings from the Swiss #2, Djokovic should not feel overly concerned by their first clash at a major.  Several of their most pivotal meetings have extended to a final set, though, such as a Rome final and a Monte Carlo semifinal.  In both of those matches, Wawrinka profited from a sluggish start by Djokovic to claim an early lead, only to watch helplessly as the Serb’s superior firepower launched a comeback.  Not since 2009 have they clashed away from clay, the surface preferred by the Swiss and arguably least favored by the second seed.  At a hard-court major, Djokovic’s more imposing first serve should prove a more decisive factor, while the competitive resilience at the root of his post-2009 rise should separate him more distinctly from Wawrinka in the best-of-five format.  More of a grinder than a shot-maker, the Swiss #2 leaned upon his fitness to survive streaky foes like Dolgopolov, but Djokovic should break down his defenses and his spirit in a match that starts with the compelling but ends with the routine.  The more elongated, physical rallies in this match should stand him in good stead for the last three rounds, though.

Roddick vs. Del Potro:  A winner under the lights in the first week, the 2003 champion hopes to shine in Primetime against a far more formidable opponent.  Favored to send him into retirement, the 2009 champion has raised his level a notch with each victory, although he has not yet faced a rival of note.  The American likewise has played with greater freedom and aggression since announcing his retirement, probably liberated from the anxieties that have clouded his mind during his decline.  Separated by Del Potro’s wrist injury are their fourth meeting and the first three, the former won by Roddick and the latter by the Tower of Tandil.  Even in his peak form during 2009, the Argentine struggled to finish off his fellow US Open champion in two North American clashes that extended to 5-5 in the final set.  Attending one of those matches at the Masters 1000 tournament in Montreal, we noticed how Roddick held the upper hand in shorter exchanges and in the mental department, whereas Del Potro enjoyed the advantage whenever the players engaged in court-stretching rallies.  The Argentine strikes his groundstrokes with much more sting than does Roddick, and he moves better than any other player of his height.  In those earlier matches, his mighty wingspan should allow him to make contact with a relatively high number of the serves so vital to the American’s game, denying the underdog the free points that he needs.  All the same, a key question remains.  Does this gentle personality have the killer instinct to snuff out the only active American man to win a major—for good?

Gasquet vs. Ferrer:  Glancing at the history between these Europeans, one struggles to summon much excitement for their ninth meeting.  All of the previous eight have ended in straight sets, with Ferrer winning seven and dominating Gasquet on every surface except grass, where they have not intersected.  At the Australian Open this year, they collaborated on a particularly dull affair at the same stage, when the Spaniard survived a few difficult service games to collect a pair of single-break sets before the Frenchman predictably folded in the third.  Seeking to reach the quarterfinals at every major in the same year for the first time, Ferrer has proven himself a player far superior to Gasquet at the crossroads that decide matches.  His comfortable Melbourne victory would not have unfolded so smoothly had he not played each point with the same intense focus, a contrast to his opponent’s passivity.  Lacking a coherent strategy against a tireless warrior like Ferrer, Gasquet ultimately attempted shots too bold to succeed consistently.  While the faster surface tilts more in his favor than does the Melbourne court, the best-of-five format will hinder him unless he can overwhelm the Spaniard quickly. 

Tipsarevic vs. Kohlschreiber:  Playing four total games against each other on a hard court before the Serbia #2 retired, they have not met on any other stage except the clay of the quasi-exhibition in Dusseldorf, the World Team Championship.  Each man has rallied from trailing two sets to one in the first week to survive, Tipsarevic from trailing two sets to love in the first round and Kohlschreiber from a daunting deficit against Isner on Ashe.  From those comebacks, one could conclude either that both men enter this odd match full of competitive mettle or that they limp into it tired and indifferent in form.  As not only a quarterfinal but a semifinal berth looms within plausible range, Tipsarevic hopes to repeat his result from last year after a generally unimpressive season at the majors.  Never having reached a major quarterfinal, Kohlschreiber could become the second straight German to accomplish that breakthrough after Florian Mayer won four matches at Wimbledon.  This match lacks title implications or a plotline of great significance, but the contrast between the Serb’s crisp two-handed backhand and the German’s flamboyant one-handed stroke should provide some lively entertainment for the more perceptive fans.