With the help of SAP analytics, wtatennis.com contributor Craig O'Shannessy gives his predictions for today's Miami Open semifinal between Serena Williams and Simona Halep.
WTA Staff

MIAMI, FL, USA - The baseline is a magnet for Serena Williams.

Nobody hugs it more, and treats it more like the finish line than the seven-time Miami Open champion.

It represents a clear line in the sand - she wants to be standing on it or slightly inside it as much as possible to execute the most lethal game plan in the modern game. Williams attacks with a variety of weapons that aim to effectively end the point before it gets started.

Firstly there is the raw power, which on its own is typically enough to gain control of most points she plays. But when you combine it with the ultra-aggressive court position, the ball gets back to the opponent so fast that it robs them of the precious tenths of seconds to get their hands and feet prepared for the next shot. Reaction mode is usually all that can be accomplished.

Take for example Williams' return position so far this year in Miami. In her run to the semifinals, she has made contact with 100% of second serve returns inside the baseline. What's shocking is that she has made contact with 81% of first serves inside the baseline as well.

There is no better way to pressure a groundstroke than right after a serve because of the court position and different technique just used, and Williams effectively takes the power of the serve and uses it as her own weapon right back at the server.

Williams is lethal off both wings, averaging 74mph with forehand returns and 67mph with backhands. Her fastest return was a 98mph forehand rocket that must have felt like a ball of lead on her opponent's racket.

SAP advanced analytics identified Williams is averaging 69mph returning first serves for the tournament, and when the first serve is missed, she increases the throttle and returns second serves 5mph faster at 74mph. Missing your first serve against Williams means significantly less time to get ready as she is also standing in further and hitting it harder. It's the most effective combo in the sport.

Overall, Williams is winning an astounding 48% of her return points, including 55% against second serves and 45% against first serves.

If the point does get developed, Williams aggressively sets up shop as you would expect right on the baseline, making contact 49% of the time inside it and 51% ever so slightly behind it. Williams does not really care if she is hitting a forehand or a backhand, as she is averaging 53% backhands and 47% forehands so far in Miami. Williams averages hitting her forehands harder (73mph to 68mph), but her fastest shot of the tournament was an jaw-dropping 115mph backhand.

Simona Halep is the next player in line having to deal with the Williams power onslaught in today's semifinal.

Halep will try and diffuse Williams aggression primarily with her forehand, where she has racked up 31 winners, to 17 off the backhand wing. A huge key in the match will be how well Halep can handle the weight of Williams' ball on her racket, and still get it deep to try and push Williams off the baseline.

Halep is averaging hitting 83% of her shots deep of the service line, and she will need to be at her very best in this key area to stay in rallies long enough to sway control of the point.

Halep's favorite part of the court to attack in her run to the semifinals is in the outer half of the ad court, where she is landing 25% of all her shots. Stretching Williams wide to the backhand will be a key strategy for Halep to stop Williams getting squarely set behind the ball and ripping it, and to also open a hole in the deuce court to finish points.

Prediction - Williams in three sets.

Craig O'Shannessy (@BrainGameTennis) is the leading analyst for wtatennis.com throughout the 2015 season, utilizing SAP Data & Insights to uncover the patterns and percentages that dominate the game. Visit Craig's website at www.braingametennis.com for more expert strategy analysis.

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