As the year’s final major beckons, a handful of notable names have a bit of unfinished business on their agenda in Cincinnati before they move on to New York.  We preview the semifinals at this Masters 1000 and Premier Five tournament.

Del Potro vs. Djokovic:  Thirteen days after the bronze-medal match, the Serb seeks revenge against a man whom he once suffocated with regularity.  Of course, the greater blow to Djokovic’s (and Serbia’s) pride came in the Olympics semifinals when Murray halted his quest for a gold medal, but leaving London empty-handed stung the recently deposed world #1 more than most of his previous setbacks.  A proud patriot and also a fierce competitor, he fought back immediately to claim the Rogers Cup title and surely would relish the opportunity to put this new nemesis in his place.  For his part, Del Potro should bring a degree of belief that he always lacked in their previous meetings, which should allow him to deploy his weapons more effectively.  Without that confidence, Djokovic wore down his fellow US Open champion in rally after rally.  Having defeated the Serb and nearly Federer as well, Del Potro should feel once again that he belongs in the elite.  An aching left wrist may complicate this narrative, for concern over his surgically repaired right wrist crippled the Argentine mentally as well as physically while he nursed and rehabilitated it.  If he can master those doubts to swing freely, on the other hand, the best might come first on Saturday.

At the core of this match is Djokovic’s ability to blunt Del Potro’s serve with his return, a task at which he excelled earlier in their rivalry before the advantage shifted to the Argentine at the Olympics.  Although the grass favors servers in general, so does the fast court in Cincinnati, as Federer could tell the Serb.  A three-time finalist here but never a champion, Djokovic has achieved much greater success on the slower courts and cooler temperatures of the Rogers Cup.  As he seeks a fourth final here, though, he has improved his form with each match and flowed seamlessly between defense and offense against Cilic.  Del Potro offers essentially the same challenge, albeit at a much higher level, so Djokovic should enter this semifinal prepared and motivated to right recent wrongs. 

Federer vs. Wawrinka:  At the tournament that he has won four times, the Swiss #1 has moved as smoothly as he has at Wimbledon, while swinging through his backhand aggressively in the most useful barometer of Federer’s confidence.  Unbroken on serve through six sets, he has permitted his overmatched opponents only a single break point.  Like fellow Wimbledon champion and Olympic medalist Serena, Federer might well succumb to complacency at this relatively inconsequential tournament and allow his thoughts to turn towards New York, where his quest for an 18th major looks highly plausible.  But Cincinnati has showcased some of his underrated virtues before, such as the conditioning routines that leave him nearly impervious to its torrid summers and the serving precision that mirrors the fast courts as well as those in New York.  Brushing aside rising star Bernard Tomic with ease, Federer laid waste almost as efficiently to Fish in the quarterfinals, an opponent who had severely tested him here two years ago. 

Against Wawrinka, to whom he has lost only once in eleven meetings, Federer rarely has played a match that creates a semblance of genuine competition.  Recalling Troicki’s matches with Djokovic, these limp affairs often feature an early break for the superior Swiss in each set and routine holds thereafter, or perhaps routine holds in one set en route to an uneventful tiebreak.  In his rousing victory over Raonic on Friday, Wawrinka displayed a snarling energy that seized all of the emotional energy on the court from the gentle Canadian giant, and Federer more subtly but similarly siphons it away from Wawrinka in their encounter.  All the same, the Swiss #2 has impressed with consecutive victories over Ferrer and the rising prodigy from north of the border.  Crushing serve-forehand combinations displayed his confidence on a surface where he has played only seven matches this year, and immediately after a four-match losing streak.  Without Federer, Wawrinka would not hold a gold medal, nor have carried the Swiss flag in the opening ceremonies.  Fortunate and unfortunate to inhabit the same era and the same nation (at least some of the year) as the greatest player ever, he should bow meekly to him again.

Li vs. Venus:  During an era in women’s tennis over which the Williams sisters have towered, only a handful of players have shown the courage to stand toe to toe with them on the most prestigious stages.  While Justine Henin stands as the most prominent example, Li Na also has not shrunk from the challenge of toppling a superstar.  She has won both of her previous meetings with Venus at tournaments of note, the Olympics and the Australian Open, in which drama compensated for the lack of quality.  On both occasions, the two women struggled mightily to control virtually their entire arsenal, alternating pinpoint shot-making with horrific misses seemingly at random.  Venus and Li share the double-edged trait of sticking to their game plans at all costs, a virtue when it works and a flaw when it fails.  Moreover, they enter this semifinal with victories over higher-ranked opponents that underscore their momentum this summer.  While Li crushed Radwanska for the second straight week, Venus outlasted Stosur in a tensely contested three-setter.

Therein may lie the key to this semifinal, for the American can draw upon shallower reserves of energy than the Chinese star, even considering that the latter won two matches in one day.  If Li can extend their battle into a draining, physical match of prolonged rallies that stretch the court, transitioning smoothly from defense to offense, she should chip away at Venus as she did in their earlier matches.  The brittle American will hope to take control from set positions on serve and return while keeping her opponent on the move and off balance with down-the-line strikes early in points.  Successful in the forecourt throughout this week, both women finish points without flinching when the opportunity presents itself, although some of their misses in those situations can cause an observer to cringe.  From a broader perspective, the meeting of these battered veterans late in a significant tournament demonstrates that tennis has evolved into a sport for experience as much as youth.

Kvitova vs. Kerber:  After a victory over the greatest female tennis player of her generation, one hardly knows what to do next.  Or so it appears, for all six of the women who have defeated Serena since her return last year have lost their next match to a mixture of opponents with varying credentials.  Aiming to halt that curious but telling skid, produced by an understandable hangover, Kerber hopes to repeat her victory over Kvitova on the red clay of Rome.  There, injury reduced the Czech lefty’s serve from a formidable missile to a tame point-starting shot, placing her in the position of starting points in neutral mode and then outlasting an opponent who moves and defends better than she does.  That formula fueled a miniature upset by the second-ranked WTA lefty over the top-ranked WTA lefty, but Kvitova’s momentum should reverse that dynamic on the Cincinnati court.  Just as Serena looked weary and sluggish in her loss to Kerber, however, the Czech will find herself in trouble if the matches accumulated in Canada and here over the past two weeks have left her arm tired and legs stiff.

An engaging contrast of styles should develop in this all-lefty semifinal, as Kvitova tries to plant herself on or inside the baseline while thrusting her opponent behind it.  This battle of court positioning should suggest who might prevail in their third career meeting and first on a relatively neutral surface.  (Whereas the red clay of Rome favored Kerber’s counterpunching, Kvitova’s victory came on a fast indoor hard court that fostered short points.)  Dogged by inconsistency for most of 2012, the Czech appears to have caught fire at an auspicious time shortly before the US Open.  On the other hand, the German has smoldered steadily throughout a season during which she has led the WTA in victories, and she has shown little sign of cooling as the summer unfolds.