After her run to the third round in Montreal last week, Watson learned that she had risen back up to No. 46 in the latest world rankings, just seven places below her career best.
But after qualifying for the main draw this time in Cincinatti, she found the world No. 31 from China, Zhang, a tough obstacle.
In a gripping encounter, Zhang eventually prevailed 6-3, 2-6, 7-5 after more than two hours in the opening match out on court six.
