Madrid, April 28 : The No. 10 seed Petra Kvitova fell victim to the first major upset in the Madrid Open while China's Zhang Zhizhen sailed into the second round of the clay court event. The Czech player, who won in Miami earlier this month, lost 7-6(9), 6-1 to Jule Niemeier of Germany here on Thursday. Croatia's 20th-seeded Donna Vekic also bowed out, following a 6-1, 7-6 (5) loss to Spain's Rebeka Masarova. Dominic Thiem advanced into the last 64 with a convincing 6-4, 6-1 victory against Kyle Edmund of Britain, who is still working his way back to his best after a knee injury, reports Xinhua. In the men's tournament, China's Zhang Zhizhen qualified for the second round, earning a 7-6(6), 6-4 victory over Jurij Rodionov of Austria in a match that lasted one hour and 30 minutes. The 26-year-old Madrid Open debutant came back from one break down in the first set and saved one set point to lead into the second set where he hit 12 winners. Former world No. 1 Andy Murray also exited in the first round, suffering a 6-2, 7-6(7) defeat to Andrea Vavassori of Italy. China's Wu Yibing crashed out in the first round as well, following a 6-2, 6-4 loss to Slovakian Alex Molcan in one hour and 21 minutes on Wednesday. In the women's doubles, China's eighth seeds Xu Yifan and Yang Zhaoxuan advanced to the next round after defeating Ekaterina Alexandrova and Anastasia Potapova 7-5, 6-2. On Wednesday, China's Wang Xiyu booked a Round-of-64 match against No. 23 seed Bianca Andreescu, thanks to a hard-fought three-set win over Varvara Gracheva, 6-7(2), 6-3, 6-4. One of the tournament's significant stories so far is the withdrawal of former US Open winner Emma Raducanu due to a hand injury, shortly before she was due to face Viktoriya Tomova in her first-round match. /IANS