Pattaya - Top seed Sabine Lisicki has struggled to reach the second round of the Pattaya Open on Monday, taking two hours to overcome Croatia's Donna Vekic 7-5, 2-6, 6-4.
Second seeded Russian Svetlana Kuznetsova eased through by defeating China's Zhang Shuai 6-0, 7-6 (3) and Chinese eighth seed Peng Shuai beat Austrian Patricia Mayr-Achleitner 6-1, 7-6 (1).
But seventh seed Bethanie Mattek-Sands of the United States was upset 6-2, 6-4 by Czech Karolina Pliskova.
Lisicki, who lost the 2013 final to Maria Kirilenko, struggled right from the start, dropping her serve in the opening game.
And although the German levelled at 2-2, Vekic broke again, led 5-3 and served for the set at 5-4 before Lisicki won the next three games.
Early in the second set Lisicki received attention to her right shoulder and Vekic went on to take the set with ease as her opponent struggled with her serve.
After an early exchange of breaks early in the final set Lisicki broke again to lead 5-3, failed to serve out the match but then broke serve again to claim victory.
"It happened during the match and as it went on it got worse and worse," said Lisicki of her shoulder. "It was really, really tough to serve at all. I couldn't serve the way I wanted and the way I usually serve.
"But the most important thing is that I fought it out. I ran down every ball. I played the finals here last year and have good memories so I really wanted to keep on playing and finish the match and not lose in the first round."
Spain's Anabel Medina Garrigues suffered the first 6-0, 6-0 defeat of her 16-year career as she lost to American Alison Riske in just 58 minutes.
Results from the first round of the Pattaya Open on Monday (x denotes seeding):
Sabine Lisicki (GER-x1) bt Donna Vekic (CRO) 7-5, 2-6, 6-4
Svetlana Kuznetsova (RUS-x2) bt Zhang Shuai (CHN) 6-0, 7-6 (3)
Karolina Pliskova (CZE) bt Bethanie Mattek-Sands (USA-x7) 6-2, 6-4
Peng Shuai (CHN-x8) bt Patricia Mayr-Achleitner (AUT) 6-1, 7-6 (1)
Alison Riske (USA) bt Anabel Medina Garrigues (ESP) 6-0, 6-0
Andrea Hlavackova (CZE) bt Estrella Cabeza Candela (ESP) 6-2, 6-4