Wimbledon champion Garbine Muguruza became the biggest casualty of the Australian Open so far – stunned by Taiwan’s Hsieh Su-Wei in straight sets on Thursday. The third seed, whose preparation was hampered by a thigh injury, was always trailing against the world number 88 before being edged out 7-6 (7-1), 6-4 in one hour and 59 minutes on Rod Laver Arena. “I knew she was going to give me a lot of pressure,” said Hsieh, who was ranked number one in doubles for five weeks in 2014. Two-time grand slam champion Muguruza struggled from the start to keep pace with the tenacious 32-year-old whose last WTA Tour singles title came at Guangzhou back in 2012. The tall Spaniard had a medical timeout at 2-5 in the first set and after having a foot re-taped looked briefly regalvanised. British hope Johanna Konta sent packing by ‘lucky loser’ Bernarda Pera at Australian Open Muguruza broke back twice but Hsieh, who works closely with former Australian Open tournament director Paul McNamee, ran away with the tiebreak 7-1. “He’s always been around me and supported me and was amazing,” she said of McNamee’s influence. “My goal to hire him at the beginning was to win a grand slam,” she added. Muguruza saved a first match point in the second set to get back to 5-4 but Hsieh made no mistake in the next game. “At 5-4 I thought I’d keep hanging there and try and take my spot,” she said. Hsieh, whose previous best at Melbourne Park was a last-16 defeat to Justine Henin 10 years ago, goes on to meet 26th seed Agnieszka Radwanska of Poland in the third round.