NEW YORK (Kyodo) -- Japan's Kei Nishikori outlasted Marin Cilic of Croatia 2-6, 6-4, 7-6(5), 4-6, 6-4 in a four-hour showdown Wednesday to reach the semifinals of the U.S. Open.
In the preceding match at Arthur Ashe Stadium, Naomi Osaka became the first Japanese woman ever to reach the singles semis at the U.S. Open after beating unseeded Ukrainian Lesia Tsurenko 6-1, 6-1.
Osaka is also the first Japanese woman to reach the last four of any Grand Slam since Kimiko Date's semifinal appearance at Wimbledon in 1996.
On another day of punishing heat and humidity in New York, 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.
"It was really tough, especially in the end," Nishikori said. "I don't know why, but we always play full sets, so it's always a battle with Marin. It was great tennis today."
Cilic, currently ranked seventh in the world, fired two consecutive aces to open the match and capitalized on Nishikori's errors to go up a set and a break.
The 28-year-old Japanese captured six games in a row to level the match and seize an early advantage in the third set, which he won in a tiebreaker with help from consecutive double faults by Cilic.
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 winner to seal the match.
"I tried to fight on every point, even though I was really tired," Nishikori said.
Later on Wednesday, two-time U.S. Open winner and former world No. 1 Novak Djokovic defeated Australian John Millman 6-3, 6-4, 6-4.
Playing in his first Grand Slam semifinal, Millman could not replicate the form that saw him defeat Roger Federer in the round of 16, allowing Djokovic to advance to the semifinals where he will play Nishikori, a player he boasts a 14-2 win-loss record over.
In the women's draw, the 19th-ranked Osaka powered past her opponent in just under an hour.
Tsurenko saw her only glimmer of hope when she held a triple break chance at 4-1 in the second set, but Osaka fought back and won the second deuce to hold serve. The 20-year-old Osaka then secured a final break to close out the match.
"It means a lot," Osaka said of her historic win. "I was freaking out inside. My entire body was shaking, so I'm really glad I was able to play well today."
Osaka, who won her first title in March at Indian Wells, will face American world No. 15 Madison Keys, who defeated Carla Suarez Navarro of Spain in the quarterfinals.
The ascendant Japanese has not managed to beat the 23-year-old 2017 U.S. Open runner-up Keys in three attempts.