The Japanese star, who lost to Cilic in his only grand slam final appearance to date four years ago, gained some semblance of revenge as he triumphed 2-6, 6-4, 7-6 (5), 4-6, 6-4 in a match that lasted four hours and eight minutes.
But after reaching the final in Monte Carlo, the French Open fourth round and the Wimbledon quarter-finals, Nishikori believes an elusive first grand slam is within reach.
On another day of punishing heat and humidity in NY, the world No. 19 Nishikori overcame an early deficit to pull out a five-set win against Cilic, who bested him in the 2014 U.S. Open final.
"Especially after coming from injury", he said. "It's always a battle with Marin", said Nishikori afterwards. "It was great tennis today".
Initially, it looked like the match might follow a similar storyline from 2014 when seventh seeded Cilic took the opening set from a sluggish Nishikori.
As Nishikori began to find his rhythm Cilic started to misfire and the Japanese collected a second consecutive break on a double fault to surge in front 5-4 before holding serve to level the match.
Though Cilic leveled at two sets apiece after the match entered its fourth hour, Nishikori hung on to grab the decisive break, smacking a forehand return victor to seal the match. "I wouldn't like to go to five sets every time but I try to fight every point and stay focused one point at a time". Millman fought back to take a 4-3 lead before Djokovic finished him off by winning the final two points of the game.
Novak Djokovic will play in his 11th consecutive U.S. Open semifinal after outlasting John Millman late Wednesday in NY.
The Japanese sputtered along until earning his first break chance at 2-4 in the second set and was able to convert to get back on serve. "I was freaking out inside".
The ascendant Japanese has not managed to beat the 23-year-old 2017 U.S. Open runner-up Keys in three attempts.