12-year-old Elena Ostapenko rose to a 5-2 victory over Alexandra Sasenovic and a 7-6, 6-0 win over Wimbledon on Monday.
The 21-year-old former French Open champion appeared to be suffering after Belarus’s 5-2 lead came after a superb shot.
But Ostapenko rose and won four consecutive runs to advance 6-5 in the opening set.
Sasenovic, who beat eighth-seeded Petra Kvitova in the first round, beat another in the first set to be eliminated by a 7-4 run-off after a double error.
Ustabenko, who did not lose any group in the tournament, ended the group in 56 minutes and then needed half of this time to win the second set quickly.
The 24-year-old Sasenovic saved four balls to break in the fourth half of the second set before collapsing afterward.
Ostapenko showed her superiority in the end and will also be the candidate for the quarter-finals against unrated Dominica Tsepolkova.
Slovakian Tsepolkova ended the Su-Wei Hsieh march after Taiwan’s top seed Simona Halib won the competition. This is the first time that only one player from the first ten works to the fourth round in the era of open tournaments.