Victoria Azarenka (1) vs. Maria Sharapova (3)
Head-to-head: Azarenka leads 5-4
What Azarenka must do to win:
Trust her shots, stay calm, and work the cross-court patterns early to establish control. Neither woman recalls Steffi Graf when it comes to court coverage, but Azarenka has been the more accurate and dangerous hitter on the run in their recent hard-court meetings. The top seed plays with more spin on her shots and has had success working the wide ball against Sharapova, whose flat replies can expire in the net. Azarenka annihilated Sharapova's second serve in the Australian Open final, winning 14 of 17 points played on the Russian's second delivery; look for her to attack that second delivery with a vengeance.
What Sharapova must do to win:
Control the center of the court, take the first strike in rallies, and serve more effectively than she did in lopsided losses to Azarenka in the Australian Open and Indian Wells' finals earlier this year. Sharapova plays a straight-forward aggressive baseline style very effectively, but she doesn't have the variety to throw a Plan B at Azarenka. The Roland Garros champion must make plenty of first serves and try to take charge of rallies early to avoid being dragged into defensive positions on court.
The Pick: Azarenka in three sets
A clash between two Grand Slam champions who are tremendous fighters—Sharapova is 12-0 and Azarenka 11-0 in three-set matches this season—should offer some crackling baseline exchanges. This could come down to which woman is making the first strike and holding her nerve on serve. Azarenka has been in better form in recent rounds, and should be empowered defeating defending champion Samantha Stosur to raise her hard-court record to 31-2 in 2012. Sharapova has been resourceful in rallying past Nadia Petrova and Marion Bartoli, but her serve has been a bit shaky recently and Azarenka is one of tennis' top returners. The Belarusian plays with more margin, which should favor her if conditions are breezy, and she's beaten Sharapova soundly in two hard-court matches this year.
Serena Williams (4) vs. Sara Errani (10)
Head-to-head: Williams leads 3-0
What Williams must do to win:
Be proactive with her feet, step inside the court to take the heavy topspin shots on the rise, and punish Errani's serve, which is by far her weakest shot. Serena remains one of the quickest women in the game and plays closer to the baseline than her opponent, but when she gets nervous her footwork can sometimes be stagnant. Serena must be quick off the mark and pounce on Errani's topspin shots, which can land short in the court, to take time away from the 10th seed. Errani is a rhythm player who finds her groove playing longer exchanges, so Serena will want to use her power to take charge early in rallies, force the Italian to defend, and use her swing volleys terminate mid-court floaters.
What Errani must do to win:
Everything, as well as she can. The feisty Italian is contesting her second major semifinal of the season and will bring all the fight she can, but she is up against an overwhelming opponent. Sara cannot beat Serena with pace or depth—Williams cracks the ball significantly harder and drives it deeper—so she must try to use her heavy spin and angle to disrupt the Wimbledon champion and extend rallies. It would help if Serena, who has had a couple of meltdowns in majors (against Kim Clijsters at the 2009 U.S. Open and against Virginie Razzano at Roland Garros in May), gets tight. It's essential the 5'4" underdog spots her spin serve effectively, as Williams can end points with one swing of her explosive returns off both wings.
The Pick: Williams in two sets
The two most important shots in tennis are the serve and return, and the 14-time Grand Slam champion is much more dangerous in both departments. Errani must try to extend exchanges, but that's a demanding task when Williams, who leads the tournament with 41 aces and has won a tournament-best 81 percent of her first-serve points, is banging her first serve with authority. Serena has won 24 of her last 25 matches and the match is clearly in her hands. Serena typically turns it up in the latter stages of Grand Slam tournaments and should be pumped to make a major statement here to continue her quest for her first Open title in four years.