Russian Karen Khachanov will play in her first Australian Open semi-final after Sebastian Korda was forced to retire with a wrist injury.
Korda was growing into the match when he began to struggle with his right wrist, taking a medical timeout midway through the second set.
The American lost seven straight on his return before retiring 7-6 (7-5) 6-3 3-0.
“Obviously that’s not the way you want to end the game,” Khachanov said.
“Up to a point it was very competitive,” he added. “Sebastian beat a friend of mine, Daniil [Medvedev] in three series and [Hubert] Hurkacz in five. He plays good tennis.”
After losing the first three games of the third set, a visibly disappointed Korda briefly sat down at the change of sides before approaching to shake Khachanov’s hand.
Korda, the son of 1998 champion Petr, then left the stadium to a standing ovation.
Khachanov will face either third seed Stefanos Tsitsipas or rising Czech star Jiri Lehecka for a spot in Sunday’s showpiece.
Olympic silver medalist Khachanov is just the 10th active male player to reach the last eight in all four major tournaments and also reached the semi-finals of the US Open last year.
Khachanov started strong but failed to serve the opener at 5-3 before taking his third set point of the eventual tie-break with a clinical backhand winner.
After a slow start, Korda had become more competitive, but he faded a lot after receiving treatment five games into the second set.
The quick set loss followed – although Korda created two break points as Khachanov briefly tightened up serving for a 5-3 lead – but the decision was made for the American as he n was able to take only one point from the first. three games of the third.
