Stefanos Tsitsipas defeated Jiri Lehecka in straight sets to set up an Australian Open semi-final with Karen Khachanov.
Greek third seed Tsitsipas reached his fourth Melbourne semi-final in five years with a 6-3, 7-6, 6-4 win.
Earlier, Russian Khachanov progressed to the final four of the Australia major for the first time when his quarter-final opponent Sebastian Korda was forced to retire with a wrist injury with the score at 7-6, 6-3, 3-Love.
On the women’s side, Victoria Azarenka continued her quest for a third Australian Open title – a decade from her last – by knocking American third seed Jessica Pegula out in the quarter-finals.
The 33-year-old Belarusian seeded 24th made a confident start and used the momentum to win 6-4, 6-1.
Pegula was the highest seed left but must wait for a first Slam semi-final.
Azarenka faces Wimbledon champion Elena Rybakina in the last four after the Kazakh beat Jelena Ostapenko 6-2, 6-4.