Barbora Strycova achieved her best grand slam singles result when she reached the Wimbledon semi-finals, but the Czech is finding it tough to build on last month's unforeseen success.

Strycova lost in the first round of the Western & Southern Open in Cincinnati, and after a first-round bye at the Bronx Open this week the 33-year-old bowed out in her opening singles match.

The third seed – long considered a doubles specialist – was beaten 3-6 6-2 6-1 by American wildcard Bernarda Pera at the WTA International tournament played in the most northerly of New York City's five boroughs. The venue is a short drive from Flushing Meadows, which stages the US Open next week.

Italian Camila Giorgi came through a tough encounter with experienced German Andrea Petkovic, grinding out a 3-6 7-5 7-6 (7-3) success.

Fifth seed Katerina Siniakova was on court for just 48 minutes, leading Anastasia Potapova 6-0 3-0 when the Russian qualifier retired.

It was one of two retirements with Zhu Lin also departing while trailing 7-6 (7-5) 4-0 to Alize Cornet.