Frenchwoman Pauline Parmentier surprised China's Jie Zheng at the Japan Open in Osaka on Thursday.
Parmentier bundled the second seed out of the tournament, notching a 6-3 6-4 win in the second round.
It took just 83 minutes to record as Parmentier – who won 74 percent of points on her first serve – won well.
She also made six breaks as she set up an exciting third-round meeting with Heather Watson of Great Britain.
Watson also knocked out a seed, sending sixth seed Anabel Medina Garrigues of Spain packing with a 6-7 (4-7) 6-2 6-3 win.
It took more than two-and-a-half hours for Watson to post victory, largely aided by the six breaks she converted from a massive 15 opportunities.
Medina Garrigues served 10 aces but failed to match her first-set intensity as Watson, who served better, claimed a terrific victory.
Other results saw South African Chanelle Scheepers beat Croatian Mirjana Lucic 6-2 6-2 and Great Britain's Laura Robson topple China's Yi-Miao Zhou 6-4 6-4.