Daily Data Viz: Caroline Wozniacki vs. Angelique Kerber in U.S. Open semifinals

A look at how No. 2-seed Angelique Kerber and Caroline Wozniacki have performed on some key points in matches ahead of their U.S. Open semifinal.

No. 2-seed Angelique Kerber and Caroline Wozniacki will face off in the U.S. Open semifinals on Thursday night. Let’s look at how they’ve performed on some the key points in matches.

As key as first serves are in the span of a match, they’re even more important on break points for these two players. Kerber especially has excelled on her first serve when the points count most but her second serve has felt the pressure.

How important is the first point of a service game?

Looking at each player’s performance when she wins the first point of her service games will give us a look at just how important that point is for both players.

Service Games WonWhen first point wonWhen first point lost

Wozniacki                   30 of 34 (88%)                      9 of 16 (56%)

Kerber                        23 of 26 (88%)                      9 of 14 (64%)

Both players have held serve at least 80% of the time coming into the semifinals. When they have won the first point of their service games, they have each won 88% of the games. When they’ve lost that first point, Wozniacki has won just 56% and Kerber 64%. 

Break Point Aversion: Key points that determine how much pressure a server faces

30-30 and deuce points are critical. As a server, if you win these points you have a game point.  If you lose these points you’re facing break points. That’s a huge swing.

30-30 and Deuce Points Won

Wozniacki: 28 of 36 (78%)

Kerber: 28 of 45 (62%)

Wozniacki has been extremely successful avoiding break points as she’s won 78% of the 30-30 and deuce points on serve. That has been key for her march to the semifinals as her service game is not really her strength and her ability to avoid a lot of potential pressure has been huge.

Kerber has won 62% of those points which has meant that she’s had to face more pressure against her serve. In a battle between these two well matched opponents, these types of points could be crucial in who has the edge.

Check SI.com's 2016 U.S. Open data hub page throughout the whole tournament for the latest data-driven infographics and charts from IBM, the official technology partner for the U.S. Open. IBM captures and analyzes the data that powers all of the Grand Slams, as well as the digital platforms that extend the experience to fans around the world.