US Open champion Flavia Pennetta suffered a surprise exit in the opening round at the Tianjin Open as she was beaten 6-3 7-5 by Lyudmyla Kichenok.
Pennetta – playing in only her second tournament since victory at Flushing Meadows – was immediately on the back foot in China as the Ukrainian qualifier broke twice in the opening set.
Her attempts to come back were futile and, after moving ahead in the match, Kichenok broke the top seed in the fifth game of the second having already wasted two previous chances.
Pennetta briefly levelled towards the end of the second set, but Kichenok found one final burst of energy to win the final two games to love and seal her second-round place.
Next up is Duan Ying-ying after she beat Nicole Vaidisova 6-3 6-3, but Kichenok's twin sister Nadiia was not so fortunate as she lost 6-4 6-0 to Urszula Radwanska.
Third seed Karolina Pliskova survived an early scare in her match with Kristina Kucova as the world number 170 took the opening set, but Pliskova upped her game and came surging through to seal a 3-6 6-3 7-5 win in two hours and 12 minutes.
Agnieszka Radwanska had no such problems in her opening match as she cruised past Olga Savchuk in under an hour, the second seed winning 6-1 6-0.
Tuesday also saw straight-set wins for Timea Babos and Danka Kovinic, while Bojana Jovanovski came from a set down - saving one match point in the process - to beat Ons Jabeur 6-7 (1-7) 7-6 (7-4) 6-1.