Down 4-1 in the second set, Bianca Andreescu roared back to deny Elise Mertens 6-3, 7-6(5) to advance to the third round at the Premier Mandatory WTA event in Beijing.

The US Open champion has now won her last 16 matches, and improves to 47-4 on tour this year. Up next for the 19-year-old is American Jennifer Brady who upset Madison Keys 2-6, 6-4, 6-4.

“She’s very strong, very powerful, hits huge strokes,” Brady said of Keys. “If you give her any time or a short ball, the point’s over. That’s really difficult, puts a lot of pressure on you especially on your own service games, trying to hold. She also has a big serve and she’s really able to dictate off her serve and first shot.”

World No. 1 Ashleigh Barty won her 50th match of the season besting Zheng Saisai 6-3, 6-7(5), 6-2 to reach the quarterfinals.

After two losses to Sofia Kenin over the summer, Elina Svitolina had her revenge beating the American 6-3, 6-7(8), 6-3.

Svitolina had three matchpoints in the second set breaker, but got it done in the third. The Ukrainian No. 1 will have a day off before a quarterfinal showdown Friday against Kiki Bertens.

Petra Kvitova also advanced over Belinda Bencic 6-3, 6-3.

“I think from the beginning, we were both a bit nervous, but I think it was a solid match from both of us,” Kvitova said. “I put in a lot of first serves, which helped me a lot, even if I was downa break in the second, which was pretty difficult mentally. She really went for her shots, but I was able to break her back. It was a good match from my side.”

On Thursday, Caroline Wozniacki continues her title defense against Katerina Siniakova and Naomi Osaka takes on Alison Riske.