The great unknown.  Serena Williams can hardly be categorized as that.  She is one of the most decorated legends of the game and a familiar face in these latter stages of the majors.  Karolina Pliskova, on the other hand, is contesting her first major semifinal and is less known to those outside tennis circles.  She has a big game and a lot of talent, though, and if she is prepared for the moment, then she might quickly become known to the wider sport's world.

A victory over Williams at any stage of a slam brings with it some level of recognition because it happens so rarely.  The American is presently seeking her twenty-third major singles title and already has seventy-one singles titles overall.  When considering all of the success she has found in doubles and the Olympics, it is no wonder many consider her one of the greatest athletes of all time.  For the better part of the last few seasons, she has played head and shoulders above virtually everyone else in the field, and the scary thing is, she does not show any signs of fading away.

As dominant as Williams may be, though, no one, including her, is invincible.  That is a fact Pliskova will hope to prove on Thursday night.  Given that she has under-performed at the slams, it would be easy to dismiss her chances, but underestimating the Czech would be a mistake.  She really started to find her form on the grass earlier this year where she won the title in Nottingham and made the final of Eastbourne, and she has had a good summer that included winning the title in Cincinnati before arriving in New York.  She is ranked just outside of the Top 10 but has been as high as world no.7 and may be ready to ascend even higher.

Pliskova definitely has a game that can help her rise in the rankings with a defeat of Williams.  She has a hard, penetrating serve that has actually garnered her more aces on the season than the top seed.  She can match Williams stroke for stroke from either wing on the baseline and arguably plays a little bit better in the forecourt.  The issue for the tenth seed is that if there is one area where Williams has a huge advantage, it is in the movement department.  As a result, she can play much better defense and is better equipped to turn that defense into offense.

Williams is also in the superior position to control her emotions in this semifinal because she has been there so frequently.  As noted earlier, she is going for her twenty-third major singles title, so she knows what it takes to come out on top in these important matches.  She has also won her only meeting with Pliskova, and she has the added security of knowing that her best is better than the best of anyone else on tour.  But Pliskova may surprise many by showing poise in this moment.  She proved she could dig deep with the way she came back and ultimately dismissed Venus Williams in the fourth round.  And while she never had any scoreboard pressure, she appeared cool, calm, and collected in her quarterfinal.  She is aware she has the weaponry to hang with and defeat Williams, and perhaps with her underdog status and the freedom it affords her, she will utilize those weapons to bring her the upset.

Of course, an upset in this semifinal is not the result most are predicting.  Williams has been too bankable through the years to bet against, while Pliskova and her response to this kind of moment is a great unknown.  If she is ready and brings her A-game, however, then this could be a blockbuster that might just end with the Czech booking a place in her first slam final.  That is a big “if,” though, and even then, history has shown that is not often enough.  Fans should still expect to see Williams advance to the final.