The top half of the draw at the National Bank Open was upended by Beatriz Haddad Maia's upset of World No.1 Iga Swiatek on Thursday, but a bevy of powerful players still fill out that side of the draw. 

Here is how the rest of the Round of 16 shook out in the top half:

Zheng Qinwen def. Bianca Andreescu 7-5, 5-7, 6-2

Zheng Qinwen is the first Chinese player to reach the quarterfinals of the National Bank Open since Li Na in 2013.

Photo by Peter Power/Tennis Canada

Zheng continues to make waves in her breakthrough season on the Hologic WTA Tour. The 19-year-old from China, who started the season ranked No.143 but cracked the Top 50 earlier in the year, bested 2019 champion and hometown hope Andreescu in just under three hours.

"I think both of us, we played our best tennis in the third set," Zheng said after her win. "At the end, I am happy that I got through the pressure and to get this match."

Zheng had 28 winners to Andreescu's 16 as the teenager ended Andreescu's eight-match winning streak in her backyard of Toronto. Zheng is into the first WTA 1000 quarterfinal of her burgeoning career.

Toronto: Zheng beats Andreescu to make 1st WTA 1000 QF of career

2022 Toronto

An overhead winner gave Zheng the one-set lead after 67 minutes. However, Andreescu reached level footing after attaining the lone break of the second set at 5-5, then serving out the set routinely.

After an early exchange of breaks in the decider, Zheng used exceptional depth and well-placed groundstrokes to reel off the final three games of the match and triumph against former US Open champion Andreescu.

Zheng will next face Karolina Pliskova in the quarterfinals. It will be their first meeting.

"I think it's really important that tomorrow I am able to level up my serve and [serving] percentage," Zheng said, looking forward to Pliskova. "Tomorrow will be a tough match, an interesting match. And I would like to challenge myself once again."

(14) Karolina Pliskova def. (3) Maria Sakkari 6-1, 6-7(9), 6-3

Maria Sakkari and Karolina Pliskova share a smile after Pliskova's hard-fought win on Thursday.

Photo by Gyles Dias/Tennis Canada

Last year's National Bank Open runner-up Pliskova prevailed in a topsy-turvy two-and-a-half-hour showdown with Sakkari. With the win, Pliskova's record is season back over .500 for the season (13-12).

Pliskova had not faced a Top 10 player this year until this match. She has now won her past four matches against Top 5 opposition.

Pliskova did not serve out the match at 5-4 in the second set, and Sakkari did not convert two set points at 6-5, either. Pliskova grabbed three match points in the second-set tiebreak, but Sakkari withstood that trio, and she converted her fourth set point to level the clash.

Pliskova regrouped and romped to a 5-1 lead in the third set, but she dropped serve in that game despite holding her fourth match point. Pliskova needed to save one final break point at 5-3 before at last converting her sixth match point to book a quarterfinal spot.

(12) Belinda Bencic def. (8) Garbiñe Muguruza 6-1, 6-3

Belinda Bencic in action on Thursday night at the National Bank Open.

Photo by Vaughn Ridley/Getty Images

Last year's Olympic gold medalist Bencic breezed into the quarterfinals with a 63-minute victory against Muguruza. Bencic improved to 2-1 against Muguruza.

Bencic saved all four of the break points she faced and converted all four of the break points she held against Muguruza. Bencic prevailed on 27 of her 32 first-service points, backing up her second-round victory over Serena Williams.

Bencic will be Beatriz Haddad Maia's quarterfinal opponent, following Haddad Maia's upset of top seed Iga Swiatek. Bencic beat Haddad Maia in Sydney earlier this year. Also, nine years ago, Bencic defeated Haddad Maia en route to her 2013 Junior Roland Garros title.