BEIJING, Sept. 29 (Xinhua) -- Third seed Alex de Minaur of Australia advanced to the semifinals of the China Open after his opponent Jakub Mensik of the Czech Republic retired while trailing 4-1 in the opening set on Monday.

De Minaur broke twice in the third and fifth games to take control before the 20-year-old Czech pulled out. The Australian had also won all three of their previous encounters.

Mensik, ranked world No. 19, has been one of the fastest-rising players this season. Starting the year at No. 49, he claimed his maiden ATP title in Miami by defeating Novak Djokovic in the final.

The 26-year-old Australian will next face world No. 1 Jannik Sinner of Italy, who defeated Hungary's Fabian Marozsan in another quarterfinal.

In women's actions, fourth seed Mirra Andreeva of Russia moved into the round of 16 with a 6-4, 6-1 victory over Spain's Jessica Bouzas Maneiro. ■