Bianca Andreescu's first match since her US Open triumph went to plan despite a brief wobble against Aliaksandra Sasnovich on Monday.

The Canadian secured a 14th straight win on the WTA Tour as she defeated Sasnovich 6-2 2-6 6-1 at the China Open.

Andreescu proved her mental strength time and again en route to her maiden grand slam success and was required to do more of the same in Beijing, seeing a straightforward opener give way to a gruelling second set.

The fifth seed recovered her composure and raced to victory in the third, setting up a clash with Elise Mertens, who gave her a real test in the Flushing Meadows quarter-finals.

"I felt like in the second set I was too tense. But she was playing really well," Andreescu said. "I think I was just getting down on myself too much.

"I think I play my best tennis when I'm a little bit more relaxed. In the third set I just wanted to stay as positive as I could and just stay relaxed, to continue going for my shots."

Mertens eased past Petra Martic 6-3 6-3 to book that match-up, but there were surprises elsewhere.


HALEP HOPES ENDED

It was announced on Monday that Andreescu and Simona Halep had secured their places in the WTA Finals.

But where Andreescu celebrated with a win to start the final Premier Mandatory tournament of the year, Halep – still troubled by a back issue – came unstuck, the sixth seed beaten 6-2 6-3 by Ekaterina Alexandrova.

Alexandrova reflected: "It was a pretty tough match, but I think she didn't play that well.

"I remember when we played last time in Cincinnati, it was tougher. But I tried to stay focused for the whole match because I knew she could play just amazing."

Jelena Ostapenko upset Karolina Pliskova on Saturday, but her run was also ended as she fell 6-2 6-1 to Katerina Siniakova.


WOZNIACKI WINS OPENER

Caroline Wozniacki has endured a tough 2019, but she marked her return to Beijing with a dominant defeat of Lauren Davis.

The Dane has won the China Open twice - including 12 months ago at the end of an outstanding season - and began her latest bid by beating Davis 6-1 6-3.

Kiki Bertens was another seed to avoid an upset, overcoming teenager Dayana Yastremska 7-6 (7-5) 6-3.

"It was tough," Bertens said. "I hadn't played her before but, of course, she hits the ball so hard, so you never really know what you're going to get."

Elina Svitolina battled back impressively in both sets against Wang Yafan to progress courtesy of a pair of tie-breaks.


BENCIC BATTLES BACK

Venus Williams saw her campaign ended by US Open semi-finalist Belinda Bencic.

The 39-year-old took the opener but went down 3-6 6-3 7-5 in the final match of the day.

Madison Keys defeated Karolina Muchova to set up an all-American meeting with Jennifer Brady, who beat 18-year-old compatriot and French Open semi-finalist Amanda Anisimova

Sofia Kenin is set to face Anastasia Pavlyuchenkova, who sunk fellow Russian Veronika Kudermetova 6-0 3-6 7-6 (7-4).