Roberta Vinci and Annika Beck suffered surprise defeats in the first round of the Guangzhou International Women's Open on Monday.
Sixth seed Vinci's tournament came to a premature end when she was beaten 6-3 7-6 (9-7) by world number 185 Zhu Lin in an hour and 35 minutes.
Wildcard Zhu reached the last 16 in the WTA Hong Kong Tennis Open last week and will be hoping to improve on that showing this week after claiming the scalp of world number 44 Vinci in her homeland.
The 20-year-old underdog won four of the eight break points that she manufactured and saved five break points to ensure Vinci fell at the first hurdle.
Zhu made a shaky start by failing to hold serve in the first game of the match, but Vinci lost her first two service games and failed to hold again in the eight set of the match to allow the Chinese to serve out the set.
Both players were more consistent on serve in the second set, with a break apiece ensuring a tie-break ensued after Vinci had failed to take two set points that came her way when she led 6-5.
Zhu needed only one match point in a lengthy tie-break to seal a shock win and send Vinci packing.
Beck also bowed in the first round, with Maria-Teresa Torro-Flor accounting for the eighth seed from Germany by securing a 6-4 7-6 (7-5) victory.
Spaniard Torro-Flor fired down four aces and progressed despite 12 double faults, as world number 58 Beck won only 50 per cent of points on her first serve.
Beck held serve only once in the first set and was broken twice in the second before failing to come out on top in a tie-break to crash out.
Second seed Alize Cornet had no such trouble as she ousted qualifier Yulia Putintseva 6-1 6-1, while American Alison Riske saw off Swede Johanna Larsson 6-4 7-6 (7-5).
Shahar Peer and Misaki Doi also advanced to the second round at the expense of Pauline Parmentier and Katarzyna Piter respectively, then Timea Bacsinszky beat Magda Linette in the final match of the day.