Olympic doubles gold medallist Katarina Siniakova added another upset to her singles resume at the Miami Open on Thursday, with a three-set comeback victory over reigning US Open champion and no 11 seed Emma Raducanu. The 25-year-old Czech, ranked 53rd in singles and the doubles world No 1, needed just under three hours to beat Raducanu and snap an eight-match losing streak against top 20 players. Siniakova won four straight games against Raducanu to reach round three in Miami for the first time in her career. Raducanu never reached match point. Siniakova was nearly reduced to tears while getting worked on during a medical timeout in the first set because of an upper-body injury, but recomposed and secured the win. “I think I just felt better as the match was going on,” Siniakova said. “I was fighting in the beginning. It was a really tough match and it could have gone either way.” For Raducanu, it was a remarkably similar result to her loss at the Indian Wells third round two weeks ago, where she started strong, but struggled to keep her consistency. Meanwhile Naomi Osaka beat Angelique Kerber 6-2 6-3 in a one-sided clash to reach the third round of the Miami Open, where Garbine Muguruza and Simona Halep withdrew with injuries. Four-times grand slam champion Osaka made a strong start against German 13th seed Kerber, grabbing an early break to go 2-0 up and dominating on serve in a 29-minute opening set. Osaka denied Kerber any chance of getting back into the match and had total control of her game as she went on to close out the 60-minute contest on her third match point when her opponent sent a forehand long. The victory was Osaka’s first against Kerber since the 2017 US Open and denied her opponent a fifth consecutive win in their head-to-head series, which the German now leads 4-2. “It is a confidence booster, but I didn’t go into the match not confident, if that makes sense,” Osaka said. “For me, it kind of just shows all the hard work that I have been doing throughout the year.” Next up for Osaka will be Czech Karolina Muchova, who beat US Open finalist Leylah Fernandez 6-4 7-6(3).