The 20-year-old sealed the win in just 66 minutes and will play either Mirra Andreeva or Ekaterina Alexandrova in the next round.

Bartunkova won five consecutive games in 19 minutes in the first set as her seventh-seeded opponent struggled to respond.

Muchova saved five set points, but it was not enough to hold back Bartunkova, who had already ousted second-seeded Aryna Sabalenka from the tournament in Beijing.

She raced into another five-game lead in the second set and gave Muchova no chance of a reprieve, forcing her into firing long to seal a win she described as a "dream come true".

"Honestly, I don't know. It was (an) unbelievable match," Bartunkova said on court.

"She's a great player and also a great human being.

"It was a really tough match today, but I was just trying to put my best tennis, and I did it."

Andreeva and Alexandrova were due to play each other later on Thursday in an all-Russian affair.