Seventh seed Shuai Peng was a surprise casualty in the first round of the Brussels Open on Tuesday.
The Chinese star was beaten 7-5 6-3 by a player ranked 32 places lower - Sweden's world number 62 Sofia Arvidsson.
Russian ninth seed Anastasia Pavlyuchenkova also suffered a shock defeat as she went down to South Africa's Chanelle Scheepers 7-5 6-2.
Eighth seed Kaia Kanepi avoided the same fate as she progressed with a 6-3 6-2 win over American Irina Falconi, while two lucky losers seized their second chances with both Lesia Tsurenko and Bojana Jovanovski progressing.
Qualifiers Arantxa Rus and Urszula Radwanska beat Jie Zheng and Varvara Lepchenko respectively, while Monica Niculescu and Yanina Wickmayer also advanced.