Kei Nishikori's US Open Final Run Further Proves Big Four's Power Is Weakening

Don't take this the wrong way—Novak Djokovic, Roger Federer, Rafael Nadal and Andy Murray aren't doing anything to lose their grip over men's tennis. It's just that an incredible group of young talent is slowly but surely ending their dominance, and the latest to burst onto the scene is Kei Nishikori.

The 10th overall seed at the 2014 U.S. Open was not given much of a chance entering Saturday's semifinal against the top-seeded Djokovic, but he won't be forgotten after mounting an epic four-set victory over the Serbian.

Nishikori looked like the best tennis player on the court from the opening set, surprising Arthur Ashe Stadium. He took an early lead thanks to his elite speed and deceptive returning power. Any time the two were hitting back and forth, it was the 10th seed—not the top seed—who was able to throw the other off with his power alone.

It was certainly a huge moment for the 24-year-old after failing to make it past a Grand Slam quarterfinal before Saturday, but as told by his post-match comments to USOpen.org, he was already focused on the final with his opponent not determined at the time of his interview:

"

Yeah, I don't really care who is in the final. You know, I have been playing well. Yeah, Roger is my idol. I always love to play. I love to watch, you know, all the time. But, you know, when you play it's different. I have to beat my idol sometimes. I have been beating him already. Yeah, it's going to be good, you know, if he wins. But, you know, I don't really care who is at the side of the net.

"

Of course, it will be No. 14 Marin Cilic and not Federer facing Nishikori in the final after the Croatian's straight-set drubbing of the second overall seed to continue the trend of unpredictable outcomes in Flushing Meadows. 

So there we have it—a Cilic vs. Nishikori final. For the first time since long before Nishikori was playing professional tennis, two players not named Djokovic, Federer, Nadal or Murray grace a Grand Slam final.

ESPN Stats and Information noted it has been nearly a decade:

Tancredi Palmeri of beIN Sports sees it as one of the biggest underdog finals in nearly 20 years:

Of course, this isn't just a trend that has cropped up over the past year with the emergence of Nishikori and Cilic. 

Juan Martin del Potro was initially the face of the post-Big Four era after winning the 2009 U.S. Open, but he's since faded while many of the Big Four—namely Djokovic and Murray—have continued to dominate the game.

Jim McIsaac/Getty Images

But 2014 has seen a big change in that dynamic, starting with Stan Wawrinka's improbable Australian Open title and ending with the crowning of another new Grand Slam champion on Monday at Arthur Ashe.

The semifinals of Grand Slam tournaments used to be reserved for the Big Four, but that hasn't been the case in 2014. Nadal has only made it past the fourth round in two of four Grand Slams, while Murray made the semis just once in 2014.

Mike Groll/Associated Press

Meanwhile, Tomas Berdych, Ernests Gulbis, Milos Raonic, Grigor Dimitrov and now a few more faces in Flushing Meadows have all made semifinal runs over the calendar year.

Nishikori's blend of speed and power makes him one of the best young players in the game, but he's not alone. From the big serves of Cilic and Gael Monfils to the tactical genius of Berdych and Raonic, the skill right outside of the Big Four is without question.

Nadal has struggled with injury concerns and Federer is on the wrong side of 30. While Djokovic and Murray are still young and on top of their games, both have shown that they just can't rip through any Grand Slam field with ease any longer.

The second tier of elite men's tennis stars is emerging, and that's a great thing for the sport as it evolves out of a dominant era for four future legends.