Alex de Minaur has moved within one match of chalking up 50 tour-level victories in a season for the first time.
And the 28-year-old has a great chance of reaching the second ATP 1000 final of his career as he is the highest-ranked player left in the top half of the Shanghai Masters draw.
Only three top-10 players remain in the tournament, with the latest to fall being De Minaur's projected quarterfinal opponent, Alexander Zverev, who lost to Arthur Rinderknech later on Monday.
De Minaur, whose only previous ATP 1000 final came in Canada two years ago, defeated Kamil Majchrzak 6-1 7-5 in humid conditions for a tour-leading 36th win on hard courts this year.
The Australian No.1 broke Majchrzak's serve five times; two of the breaks came after he dropped serve to trail 4-3 in the second set.
"I came into this week knowing how tough the conditions were going to be," De Minaur said. "So the mindset ultimately is surviving, finding ways, and getting ready for battles every time you step out on the court.
"There is no such thing as easy matches, especially in these conditions, so I'm glad I was able to compose myself in the second set, get the break back, and finish it off in two. If we had gone into a third, it would have been very physical."
De Minaur will next face Nuno Borges, who defeated Shang Juncheng 7-6(5) 4-6 6-3. The world No.7 has yet to play the 28-year-old Portuguese, who is ranked 51st.
The winner will meet either fast-improving American Learner Tien, who defeated Cameron Norrie 7-6(4) 6-3, or 16th-seed Daniil Medvedev, who beat Alejandro Davidovich Fokina 6-3 7-6(5).
Also progressing in Shanghai was Felix Auger-Aliassime, who converted three of four break points to defeat Jesper de Jong 6-4 7-5. Auger-Aliassime will next face eighth-seeded Lorenzo Muzetti, who defeated fellow Italian Luciano Darderi 7-5 7-6(1).
The Shanghai Masters draw began breaking wide open when world No.2 Jannik Sinner, the defending champion, retired due to cramps when trailing Tallon Griekspoor on Sunday.
Top-ranked Carlos Alcaraz, who won the Japan Open last week, is not in Shanghai due to minor ailments.