Garbine Muguruza of Spain in action against Aryna Sabalenka of Belarus. (Reuters)

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Sabalenka, who claimed her second title of the season at the Wuhan Open last week, edged a tight opening set and the Belarusian took control in the next to overpower Spaniard Muguruza and secure victory in an hour and 46 minutes.

Former French Open champion Ostapenko struggled with a wrist injury before losing to local hope Wang in 55 minutes.

Guangzhou champion Wang, who has won 14 of her last 17 matches, next plays former world number one Karolina Pliskova or Aliaksandra Sasnovich.

World number three Angelique Kerber fought back from 5-3 down in the first set to beat Carla Suarez Navarro 7-6(4) 6-1.

US Open champion Naomi Osaka crushed Danielle Collins 6-1 6-0 to set up a clash with 10th seed Julia Goerges who beat the Japanese the last time they met in Charleston this season.

American Sloane Stephens took advantage of an error-prone display by China's Zheng Saisai to win 6-1 6-3 and set up a clash with Dominika Cibulkova who beat Daria Gavrilova 6-3 6-3.

On the men’s side, US Open finalist Juan Martin del Potro swatted aside Spain's Albert Ramos-Vinolas 7-5 6-2 on Tuesday to reach the China Open second round.

Juan Martin del Potro of Argentina in action against Albert Ramos Vinolas of Spain. (Reuters)

Del Potro, playing his first match since losing to Novak Djokovic in the US Open final last month, looked in fine form as he fired 10 aces and won 86 percent of points on his first serve to seal victory in 90 minutes.

The 30-year-old Argentine can qualify for next month's ATP Finals in London for the first time since 2013 if he reaches the final in Beijing. He plays Russia's Karen Khachanov next.

Rafael Nadal, Djokovic and Roger Federer have secured their places in the season-ending tournament.

Bulgaria's Grigor Dimitrov, a finalist in Beijing two years ago, began his campaign with a solid 7-5 6-3 victory over American Tennys Sandgren.

Spain's Fernando Verdasco was made to work hard before beating France's Gael Monfils 2-6 7-6(3) 7-6(5) in two hours and 23 minutes.