Wimbledon champion Halep seeded four, earned a late break in the penultimate game of the final set to reach the third round after two hours of action.
Halep has finished runner-up in Cincinnati three times, last reaching the final a year ago against Kiki Bertens.
In the next round, the 27-year-old Romanian, who retired injured from her Toronto quarter-final against Czech qualifier Marie Bouzkova last week, will next face either Madison Keys of the United States or Russia’s Daria Kasatkina.
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