Australian No.2 Ajla Tomljanovic has progressed to the last 16 of the Zhengzhou Open after a comprehensive 6-2 6-0 victory over Dutch qualifier Lesley Kerkhove on Tuesday.

World ranked 46 Tomljanovic was in ruthless form to see off her opponent in just under an hour to secure a tough clash with world No.7 and third-seed Kiki Bertens.

American Alison Riske fought back from a set down to beat Germany’s Angelique Kerber 5-7 6-4 7-6 (86) in the first round of the inaugural event, extending the former world No.1’s poor run of form.

Riske held her nerve to save a match point in the third-set tiebreak before going on to inflict a fourth consecutive first-round defeat on Kerber, who was beaten by Kristina Mladenovic in her first match at the US Open.

The German, a three-times Grand Slam champion, was beaten in the second round at Wimbledon and suffered first round defeats in Toronto and Cincinnati in the run-up to the year’s final Grand Slam at Flushing Meadows.

Mladenovic made short work of Chinese wildcard Duan Yingying earlier in the day, winning 6-2 6-3 to set up a second round meeting with fellow Frenchwoman and her former doubles partner Caroline Garcia.

Former French Open champion Jelena Ostapenko beat 23-year-old Chinese qualifier You Xiaodi 6-3 0-6 6-2 to reach the last 16, while France’s Fiona Ferro and Alize Cornet also advanced.

Also in China, Australian No.6 Samantha Stosur booked her place in round two of the WTA Nanchang event, seeing off compatriot Arina Rodionova 7-6 (8-6) 6-3.

Fellow Australian Zoe Hives also scored a fine win when she put out fourth seed Anastasia Potapova 6-7 (7-4) 6-4 6-4 at the Japan Open, the Russian committing 15 double faults.

Top seed Su-Wei Hsieh started her title defence in Hiroshima with a hard-fought 6-1 3-6 6-3 win over Risa Ozaki.

The home wild card recovered to force a decider as the crowd sensed an upset, but world number 29 Hsieh proved too strong as she closed out victory in just under two hours.