Alison Riske began 2016 in fine style, edging a three-set marathon against eighth seed Annika Beck to advance to the second round of the Shenzhen Open.
World number 97 Riske ended 2015 with eight defeats in nine matches, having progressed past the second round in just three tournaments all year.
But a 6-7 (3-7) 6-3 6-2 triumph over the German - ranked 39 places above her - gets the new year off on the right foot and Riske is rewarded with a second-round tie against Hsieh Su-wei, who toppled Chinese wildcard Duan Yingying 6-4 7-5, with second seed Petra Kvitova a likely quarter-final opponent for the winner.
Beck was the only seed to fall on Monday, Irina-Camelia Begu (3), Monica Niculescu (4) and Zarina Diyas (7) each progressing.
Begu and Diyas sailed through on the back of straight-set wins over Lara Arruabarrena and Zhang Kailin respectively, with Niculescu recovering from a first-set wobble to beat Anastasija Sevastova 1-6 6-4 6-3.
Timea Babos, Katerina Siniakova and Anna-Lena Friedsam were straight-set victors in the day's other matches.