Stosur, who won the tournament in 2009 was runner-up in 2011, broke serve five times and hit five aces in the 69-minute match.
Meanwhile, second seed Sabine Lisicki has withdrawn from the tournament due to a hip injury. The German had been scheduled to face Slovenia’s Polona Hercog in the second round on Thursday but has pulled out ahead of the match.
Elsewhere, Angelique Kerber can take a step closer to clinching the final spot at the season-ending WTA Championships at Istanbul with victory over Monica Niculescu in the first round in Osaka.
German top seed Kerber can guarantee her spot at the season finale by reaching the semi-finals of the Japan Open, or by making the last eight of the Moscow Open next week.
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