It was a case of sweet revenge for Kei Nishikori as he outlasted Marin Cilic on Wednesday, four years after losing to the Croatian player in the final of the US Open.
A short while after her win, Kei Nishikori held off Marin Cilic in five sets to mark the first time in the Open era that a Japanese man and woman advanced to the semifinals at the same Grand Slam.
There was a subdued atmosphere on Arthur Ashe Stadium with the crowd struggling to get into the match.
But Cilic, US Open champion in 2014 refused to back down and took the match into a decider by winning the fourth set 6-4.
In the other men's quarterfinal Friday, giant killer John Millman, fresh from his shock victory over five-time champion Roger Federer, takes on Novac Djokovic with the 55th-seeded Australian looking to add another upset to a storybook tournament so far.
With Nishikori playing immediately after Naomi Osaka on Wednesday, the U.S. Open became must-see viewing for Japanese tennis fans.
Nishikori won the opening two games of the third to make it six games in a row before surviving six deuces to come through a marathon sixth game.
The 20-year-old Osaka said she was nervous, claiming to be "freaking out inside" - though it certainly never showed.
Osaka was an easy victor in her quarterfinal, eliminating unseeded Lesia Tsurenko of Ukraine 6-1, 6-1 in all of 57 minutes.
The Ukrainian had a small window to grab momentum but failed to cash in on her three break-point opportunities while trailing 4-1 in the second set and Osaka fought back before cruising through the final game.
"The quarters was sort of my mental goal, every time I played a Grand Slam", said Osaka. She won 20 of her 22 first serves, and she broke Tsurenko's serve five times.
She pushed some balls a few feet past the baseline, often failing to make Osaka do anything special to win a point and finishing with 31 unforced errors.
"Just like my entire body was shaking, so I'm really glad I was able to play well today", she said. The 14th-seeded American used her big-strike game built on serves and forehands to overpower No. 30 Carla Suarez Navarro of Spain 6-4, 6-3 in the quarterfinals at Flushing Meadows on Wednesday night. This will be Keys' second consecutive semifinal appearance at the US Open.
Serbian sixth seed Djokovic, who will cap the night session, is in familiar territory, appearing in his 11th quarter-final at Flushing Meadows, and looks like a favourite with five-times victor Roger Federer knocked out of his half of the draw.