And then there were four.
The men's semifinals for the 2018 U.S. Open are set after the conclusion of Wednesday's two quarterfinal showdowns. No. 21 Kei Nishikori and No. 6 Novak Djokovic joined No. 1 Rafael Nadal and No. 3 Juan Martin del Potro in the semifinals after beating No. 7 Marin Cilic and unseeded John Millman, respectively.
Nadal and del Potro advanced to the semifinals Tuesday.
The top seed needed the full five sets against No. 9 Dominic Thiem in one of the most thrilling matches of the tournament, while del Potro handled American John Isner in four sets.
With the quarterfinals in the books, here is a look at the schedule for the semifinals.
2018 U.S. Open Men's Semifinals Schedule
No. 1 Rafael Nadal vs. No. 3 Juan Martin del Potro, Friday on ESPN
No. 6 Novak Djokovic vs. No. 21 Kei Nishikori, Friday on ESPN
Nadal facing del Potro in the latter rounds of a major is becoming the norm for tennis fans.
The Spaniard star holds an 11-5 advantage in head-to-head matchups, and Stanley Kay of Sports Illustrated noted this will be the fourth time in the last five Grand Slam tournaments they play each other. Nadal defeated del Potro in last year's U.S. Open, this year's French Open and this year's Wimbledon in a classic quarterfinals showdown.
Nadal won the Wimbledon clash in five sets, 7-5, 6-7, 4-6, 6-4, 6-4, providing a glimpse at what fans in New York may be in for in this semifinal matchup. Del Potro appeared on the verge of winning multiple times before the top-ranked player was able to bounce back and seize control down the stretch.
Del Potro did beat Nadal and Roger Federer on his way to the 2009 U.S. Open championship before wrist injuries cost him during his prime.
He is playing at a career-best ranking, though, and fatigue figures to favor him if it comes into play. Nadal needed five sets and two tiebreaks in the quarterfinals, four sets and a tiebreak in the fourth round, and four sets and two tiebreaks in the third round. Del Potro won each of his matches in straight sets except for the quarterfinal, when he needed four sets to beat Isner.
Still, it is impossible to ignore the head-to-head results on the game's biggest stages when projecting this matchup. The thought here is Nadal continues to serve as an obstacle del Potro cannot overcome in his career revival.
As for the other semifinal, Djokovic holds a commanding 14-2 advantage over Nishikori in head-to-head matchups, although one of the latter's victories came at the 2014 U.S. Open semifinals.
The Serbian star is also playing well this summer and won the Western & Southern Open in Cincinnati, won Wimbledon and reached the final at the Fever-Tree Championships in London. BBC noted his victory over Federer in Cincinnati made him the first men's player in the sport's history to win all nine Masters 1000 tournaments.
It stands in contrast to Nishikori, who is yet to win a title this year.
Djokovic eliminated him at Wimbledon in the quarterfinals and in Masters tournaments in Rome and Madrid this year. Djokovic has dominated Nishikori in their matches recently and throughout their careers, and there is no reason to think things will change in New York.
Get ready for a star-studded final.
Prediction: Nadal and Djokovic win their semifinal matchups and square off in the championship match.