As Cincinnati concludes, we review each of the semifinals from Saturday.

Federer d. Wawrinka:  After today’s match, the 17-time major champion has won 21 of his last 22 sets against his compatriot and doubles partner en route to a 2008 gold medal.  Likely grateful for Federer’s role in his career, Wawrinka capitulated to him again on Saturday despite keeping the match closer than one might have expected.  Neither man dropped serve in the first set, during which the Swiss #2 fought off seven break points while garnering just one of his own.  Landing fewer than half of his first serves, Federer nevertheless snuck away with the set in a tiebreak and then won the second more routinely.  The match ended in the typically anticlimactic fashion of this non-rivalry when he broke his countryman’s serve for a second time.  Doubtless happy to have reached this stage, Wawrinka will not feel overly disappointed, and he can console himself with the reminder that he earned twice as many break points on Federer’s serve (two) as his first three opponents combined.  Not having surrendered his serve in the tournament, the top seed will pursue a record fifth Cincinnati title and record-tying 21st Masters 1000 shield on Sunday.

Djokovic d. Del Potro:  Hampered by a left wrist injury, Del Potro submitted a meager effort in a semifinal less scintillating than one might have expected.  Vengeance was the Serb’s after a tepid 88 minutes in which he saved all six break points on his serve.  Somewhat more competitive than the scoreline suggested, the match could have tilted in the Argentine’s direction when he earned a string of break points early in the first set to take a lead and another break point to draw even midway through the second set.  Djokovic’s resilience on serve thus played the dominant role in his commanding victory, as did his ability to trouble Del Potro even on his first serve, winning nearly 40% of those points.  Since the Olympics, the defending US Open champion has saved 37 of 38 break points; like Federer, he has not lost serve this week.  Into the Cincinnati final for the fourth time in five years, Djokovic will hope to make the fourth time the charm after three runner-up finishes.  Del Potro will travel to the Mayo Clinic in Rochester, Minnesota for an examination of his aching left wrist, and he will hope for a less serious injury than he suffered to his right wrist in 2010.

Li d. Venus:  As it has so often this year, the fatigue of long matches early in a tournament finally caught up to Venus during a listless, sluggish final set, exacerbated by a back strain that worsened as the match progressed.  Even her fearsome serve clanked through the court at less than 80 mph on several occasions, and she barely moved to cover some of Li’s penetrating groundstrokes.  Before that disappointing denouement, however, the two champions engaged in two sets of absorbing if far from aesthetically pleasing tennis.  Jolting in a staccato rhythm, their match featured a heaping helping of botched service returns and woefully mistimed groundstrokes.  But it also showcased a reasonable number of sparkling winners and precisely placed serves.  Trailing for almost the entire match, Venus competed impressively despite languishing at a level far too inconsistent to topple an opponent as steady from the baseline as Li.  All the same, she will feel satisfied with her US Open preparation and not overly concerned about the prospect of facing a seeded player there in the first or second round.  For Li, a second straight Premier Five final in North America represents the best possible start to the second half after an uneven first half of 2012.

Kerber d. Kvitova:  A wilder rollercoaster than the other women’s semifinal preceding it, this match began with the German lefty racing out to a set-and-break lead as she won eight of the first ten games from a jaded Kvitova.  Unable to convert any of her seven break points in the first set, last week’s Rogers Cup champion allowed the frustrations to poison the rest of her game and donated too many unforced errors to stay competitive.  Just when the finish line started to loom for her opponent, Kvitova suddenly dialed back into focus and reeled off six straight games to cruise through the second set and start the third optimistically.  Striking her targets with breathtaking accuracy late in the second set, she often left Kerber frozen without time to react, despite her efficient movement.  That mid-match surge subsided amidst a sequence of poor errors in the fifth game of the final set, which handed the momentum back to the German for good—more or less.  With her back to the wall, Kvitova responded with a burst of resistance in breaking Kerber when she served for the match at 5-2 before holding serve in the next game, saving a match point with an ace.  On her second attempt, however, the German closed out the match with minimal ado, avoiding further flashes of startling brilliance from across the net and benefiting from the last of more than 50 unforced errors from the Czech.  In her first Premier Five final, Kerber must count herself the underdog again when she faces Li.  But this match improved her record to a sparkling 18-1 in third sets this year, so she should feel confident if another long match develops.

Read the previews of the Cincinnati finals tomorrow morning at sharapovanovic.com.