Novak Djokovic reached the US Open semifinals after his victory over John Millman who toppled Roger Federer in quarterfinals.
The 31-year-old Serb earned a 6-3, 6-4, 6-4 win on late Wednesday over the No.55 seed Australian in Arthur Ashe Stadium, New York.
"All credit to John," said Djokovic after the win. "He is a great fighter."
"He deserves a round of applause, definitely," Djokovic said.
Japan's Nishikori beat Croatia's Marin Cilic to reach his third US Open semifinals, 2-6, 6-4, 7-6, 4-6, 6-4.
"It is always a battle with Marin. It was great tennis today," Nishikori said.
He will face Djokovic to claim a berth in the US Open final
American Madison Keys, the 14th seed, reached the US Open semifinals, defeating Carla Suarez Navarro, 6-4, 6-3.
"To break in both sets, having solid games there, was really important tonight," Keys said after her victory.
Japan's 20-year-old Naomi Osaka reached her career-first Grand Slam semifinal at US Open after a victory over Ukrainian Lesia Tsurenko, 6-1, 6-1, in Arthur Ashe Stadium.
"It means a lot...I was freaking out inside. My entire body was shaking, but I was really glad I was able to play well today," Osaka said after the match.