Many top names continued to grind their way past tough competitors, but some up-and-coming stars made their mark on Wednesday. These are the Top 5 photos from Cincinnati.
1. Romanian Simona Halep had her back against the wall in the second round, but recovered against Ekaterina Alexandrova to win, 3-6, 7-5, 6-4. In the third round, Halep will face Madison Keys; the Wimbledon champion has only lost once in six head-to-head matchups with the American.
2. Ashleigh Barty's second-round match against Maria Sharapova was initially evenly contested, but the world No. 2 broke the match open to eventually prevail, 6-4, 6-1. Barty suffered an opening-round exit in Toronto last week to relinquish the No. 1 ranking and is aiming to recapture the same form that saw her triumph at the French Open.
3. Yoshihito Nishioka had a day to remember after facing compatriot Kei Nishikori. The 23-year-old advanced past the world No. 5, 7-6 (2), 6-4, for his first Top 10 victory and said after he wanted to "just try my best against my hero." Having come through the qualifying rounds, his encounter Thursday with Alex de Minaur will be the Japanese's fifth match in the past six days.
4. Naomi Osaka outlasted Aliaksandra Sasnovich in a two-hour plus battle. The reigning US Open and Australian Open champion defeated the Belarusian, 7-6 (3), 2-6, 6-2, to advance to the third round in Cincinnati. Osaka will face the crafty Hsieh Su-wei in Thursday's TC Plus Match of the Day.
5. Jan-Lennard Struff posted a 6-4, 6-7 (5), 7-6 (6) upset against world No. 7 Stefanos Tsitsipas to advance to the third round. Wednesday's win gave the German his fifth victory in his past 10 matches against Top 10 opponents and saw Tsitsipas fall in his opening match for the second week in a row.