Britain's Heather Watson has been knocked out of the Cincinnati Open in the second round by Australian world number one Ashleigh Barty.
Barty won 6-4 7-6 (7-3) and now meets defending champion Victoria Azarenka of Belarus in the last 16.
Naomi Osaka progressed with a three-set victory over American teenager Coco Gauff, winning 4-6 6-3 6-4.
The Japanese second seed will now face Swiss Jill Teichmann for a spot in the quarter-finals.