CINCINNATI - Second seed Stan Wawrinka slumped to defeat as Grigor Dimitrov staged a 6-4, 6-4 upset at the ATP-WTA Cincinnati Masters on Thursday to reach the quarter-finals.
Grigor Dimitrov of Bulgaria hits a return to Stan Wawrinka of Switzerland on August 18, 2016 in Mason, Ohio
Wawrinka, coming off a back problem which kept him from the Rio Olympics, fell victim to the Bulgarian who has been fighting back from a poor season.
The Swiss star did not help his cause with 28 unforced errors and just 11 winners in a contest that finished inside 90 minutes.
Dimitrov, playing doubles with Wawrinka this week as the US Open start approaches a week from Monday, stretched his lead in the series to 4-2. The Bulgarian is through to his fourth Cincinnati quarter-final.
In the women's third round, 15th seed Karolina Pliskova of the Czech Republic defeated Japan's Misaki Doi 7-5, 6-3.