Tsitsipas powers past Lehecka into Australian Open semi-finals
The Greek third seed proved too powerful for unseeded Czech Jiri Lehecka on Rod Laver Arena, storming home 6-3, 7-6 (7/2), 6-4.
He will face the Russian 18th seed Khachanov for a place in his first Melbourne Park final, having crashed in the semis three times previously, including in the past two years.
Russia's Khachanov booked his place when American Sebastian Korda retired hurt with a wrist injury while trailing 7-6 (7/5), 6-3, 3-0.
"It felt different this time from any other match and the most important thing in the end is that I found a solution," said Tsitsipas, who will become world number one should he win the title.
Novak Djokovic can also achieve the feat if he does the same.
"It was a very difficult three-setter, one of the most difficult so far in the competition," added Tsitsipas, 24.
"Jiri had a very good tournament, he's started playing very well recently. He's a great player.
"I had to deal with his groundstrokes, which were coming over the net much heavier and deeper, so that was a task where I really had to put my heart out there and give it my best," he added.
Lehecka, ranked 71, warned Tsitsipas before the match he wanted revenge after losing to him in the semi-finals at Rotterdam last year.
But the 21-year-old, who beat 11th seed Cameron Norrie and sixth seed Felix Auger-Aliassime en route to the last eight, was immediately under the gun.
Tsitsipas worked five break points on his opening service game and got over the line when the Czech smacked a backhand volley wide.
He consolidated for a 3-0 lead and with his strong first serve offering Lehecka few opportunities to strike back, coasted to the first set in 36 minutes, sealing it with an ace.
Tsitsipas saved five break points to hold in a crucial third game of the second set as Lehecka came alive and began applying pressure.
Both players dug in and it went with serve to a tiebreak, where the Greek kept his cool to take an early advantage that he never gave up.
In a close third set, Tsitsipas' second double fault of the night handed Lehecka three break points in game seven.
But he saved them all to hold, pumping the air in celebration.
With the bit between his teeth, the Greek star dialled up the pressure as Lehecka served to stay in the contest and a crosscourt backhand earned him a match point which he converted.
