The 2013 U.S. Open has stayed true to form and the unpredictable has transpired.
The question is, how can Wawrinka pull off an upset against the world's No. 1 player and continue his magical run through the U.S. Open?
Wawrinka has overcome one of the most difficult draws of anyone in New York City to reach the semifinals. In chronological order, he's defeated Radek Stepanek, Ivo Karlovic, Marcos Baghdatis, No. 5 Tomas Berdych and No. 3 Andy Murray.
He dismantled Murray, the defending U.S. Open champion, 6-4, 6-3, 6-2 in straight sets.
Up next, however, is Wawrinka's greatest test yet, as he's set to face Djokovic in the semifinals. This is their second Grand Slam meeting of the year, after the 2013 Australian Open when Djokovic needed 22 games to win the fifth set and advance 1-6, 7-5, 6-4, 6-7 (5-7), 12-10.
Here's how Wawrinka can experience similar success, but change the end result.
In the 2013 U.S. Open, Wawrinka ranks eighth amongst all players with 45 total aces in five matches, per USOpen.org. Furthermore, Wawrinka has won 79.3 percent of his first-serve points and an impressive 58.1 percent of his second-serve points.
If the Swiss star is to upset Djokovic, he'll need to maintain those outstanding percentages.
Wawrinka has reached the semifinals by pulling out powerful and well-placed serves that enable him to earn quick points. He's also used his serve to take early control in long baseline rallies, which is an inevitable aspect of a match against Djokovic.
If he fails to serve well, however, Wawrinka will pay the consequences.
Most importantly, Djokovic leads all players with 34 break points won, per USOpen.org.
Against Murray, a player whose ability to break service is similar to Djokovic's, Wawrinka managed to win an astonishing 88.1 percent of his first-serve points. Wawrinka also stayed true to his tournament statistic by winning 58.9 percent of his second-serve points.
Per AustralianOpen.com, Wawrinka only won 62.1 percent of his first-serve points when he nearly defeated Djokovic at the 2013 Australian Open. If he can hold service in the semifinals, a win is feasible.
Work the Net
The art of the serve-and-volley has become more of a complementary skill than a true style of play in recent years. Once the source of success for decorated players such as Pete Sampras and Patrick Rafter, volleying is now a situational skill.
At the 2013 U.S. Open, however, Wawrinka has won matches with his ability to play at the net.
According to USOpen.org, Wawrinka was 31-of-42 on net approaches during his upset of Murray in the quarterfinals. That equates to 73.8 percent, but the true number that should impress is 42.
By comparison, Murray, a capable player at the net, came up for volleys on 22 points, per USOpen.org—a full 20 less.
This is a critical approach for Wawrinka, as he became a baseline striker during his fourth round win over Berdych and occasionally dug himself into a one-dimensional hole. Considering he was 11-of-15 when he did come to the net, via USOpen.org, his unwillingness to go to his volley game was surprising.
Fortunately, he returned to what works against Murray.
If that's not enough, AustralianOpen.com reports that Wawrinka was 40-for-58 on net approaches during his marathon loss to Djokovic at the 2013 Australian Open. When you come that close, you don't change your approach.
Not what worked, at least.
Avoid Long Rallies
If Wawrinka is going to defeat Djokovic, he's going to need the perfect storm. The world's No. 1 isn't only a strong competitor, but he has one of the most fierce combinations of accuracy and power of any baseline player.
For that reason, Wawrinka needs to end points as quickly as possible.
This approach has worked well for Wawrinka, as he owns just one of the 20 longest rallies at the 2013 U.S. Open, per USOpen.org. Against Murray, that strategy was used to perfection, as Wawrinka won 92 percent of points that lasted three strokes or shorter, per USOpen.org.
So why fix what isn't broken?
Djokovic is more than capable of hitting passing shots to take away Wawrinka's advantage at the net, which can frustrate a player who employs the serve-and-volley. But Wawrinka is a powerful player who uses his body well, specifically while volleying.
As tempting as it is to test wits against the world's No. 1, Wawrinka will only win if he plays to his own strengths.
If he can force Djokovic to reach for return shots, Wawrinka can charge the net and hold service in a quick manner. If he's unable to do that, however, the Swiss star's deep U.S. Open run will end in the semifinals.
No formula is guaranteed to be successful, but if Wawrinka follows this one, he will have his best chance of reaching the U.S. Open final.