American Madison Keys put on a show for the fans in Cincinnati as she upset 12th seed Timea Bacsinszky 6-4, 6-3 on Monday.
Keys broke Bacsinszky right off the bat before going on to take a 2-0 lead. However, Bacsinszky brought herself level at 2-2 after breaking Keys in the fourth game of the set. But, the 20-year-old broke right back and remained one step ahead until she closed out the first set 6-4.
Bacsinszky held serve to take a 1-0 lead at the start of the second set before Keys came roaring back by winning the next three games.
Backsinszky made things interesting when she fought back to make it 4-3 in Keys' favour, but the American proved to too much to handle as she broke the 26-year-old in the ninth game of the set before converting her second match point to finish off Bacsinszky in an hour and 35 minutes.
Keys did not provide the only upset of the day as ninth seed Garbine Muguruza lost to Kazakhstani qualifier Yaroslava Shvedova 6-4, 7-6 (0).
Meanwhile, 14th seed Elina Svitolina and 15th seed Andrea Petkovic both advanced to the second round, along with Varvara Lepchenko, Tsvetana Pironkova, Timea Babos and Irina-Camelia Begu.