Karen Khachanov harnessed the confidence he took from making the US Open semi-finals to match the feat at the Australian Open on Tuesday, helped by Sebastian Korda retiring hurt.
Korda needed treatment on a wrist injury in the second set of their quarter-final before calling it quits when trailing 7-6 (7/5), 6-3, 3-0 to the Russian 18th seed on Rod Laver Arena.
Khachanov's reward is a clash with either Greek third seed Stefanos Tsitsipas or unseeded Czech Jiri Lehecka, who play later, for a spot in Sunday's final.
Victory equals the 26-year-old Khachanov's best performance at a major after his semi-final run at last September's US Open, where he lost to Norway's Casper Ruud.
He said his deep run at Flushing Meadows helped immensely.
"I would say I always believed in myself, but there are always ups and downs and sometimes when you have this great result (at US Open), it just shows you what you're capable of," he said.
"And then you start to believe more and more. So this belief and self-confidence, I think, appeared much stronger after the US Open.
"I just hope to continue that way and to grow as a person and as a sportsman."
The Olympic silver medallist, who has won four Tour-level titles, came into the match with far greater experience at this stage of a Grand Slam than the American Korda, having reached the last eight at all four majors.
In contrast, the 22-year-old Korda -- attempting to emulate father Petr's 1998 title run -- was in his first quarter-final.
Khachanov also had an easier ride in the fourth round, routing Japan's Yoshihito Nishioka in straight sets while Korda slogged through a five-set thriller against Hubert Hurkacz.
- Pain -
The Russian, who reached a career-high ranking of eight in 2019, opened with a serve to love, then reeled off an easy break to go 2-0 clear with Korda's early nerves apparent.
The American finally got off the mark to hold for 3-1 but with Khachanov blasting down aces and winning more than 90 percent on his first serve, the chances to break back were few and far between.
However, a wayward backhand as he was serving for the set handed Korda his first break-point opportunity and he grabbed it with both hands.
It went to a tiebreak, where Khachanov held his nerve, sealing it on his third set point with a blistering backhand down the line.
Korda needed treatment on his right, serving, wrist at 3-2 in the second set. He returned with it strapped but was immediately broken.
The Russian consolidated and with Korda struggling, flexing his wrist between points, he broke again to take a two-set lead.
Korda left the court at the changeover, clearly in trouble. He continued but lost the opening 10 points of the third set before retiring.
"Some forehands I couldn't even hold the racquet. Volleying was almost impossible for me, so it was a little tough," said the American.
He first felt the injury at the Adelaide International this month, but it had not bothered him in the opening four rounds at Melbourne Park until he hit a return in the second set.
"Now it just came back out of nowhere," he said.
Khachanov said it was always disappointing to win when someone retired and acknowledged Korda's good form.
"He beat my friend Daniil (Medvedev) in three sets and won in five sets against Hurkacz so you know he is playing great. So applause to him," he said.