China's Qinwen Zheng took advantage of a last-minute entry into the San Diego Open to advance to the second round on Tuesday.Zheng, a lucky loser from qualifying, got into the field when reigning Wimbledon champion Elena Rybakina of Kazakhstan pulled out because of an illness.Zheng then jumped out to a 5-0 lead on Garbine Muguruza of Spain before the 2017 Wimbledon champion retired because of a gastrointestinal illness.Zheng's brush with top foes will continue in the second round when she opposes Poland's Iga Swiatek, the reigning French Open and U.S.
Open champ, in the second round.Other first-round winners on Tuesday included eighth-seeded Daria Kasatkina of Russia, the Czech Republic's Karolina Pliskova and the United States' Sloane Stephens.
Croatia's Donna Vekic upset fifth-seeded Maria Sakkari of Greece 7-6 (3), 6-1.In the last match of the night, sixth-seeded Coco Gauff led qualifier Robin Montgomery 6-3, 3-2 in an all-U.S.
showdown that was suspended due to rain. The match will conclude on Wednesday.Transylvania OpenFourth-seeded Anastasia Potapova of Russia topped the United States' Ann Li 6-2, 7-6 (5) in the first round at Cluj-Napoca, Romania.Potapova converted eight of her 12 break-point opportunities while Li was 6 of 12 in that category.Second-seeded Anhelina Kalinina of Ukraine moved on when Canada's Eugenie Bouchard retired due to a hip flexor injury after losing the first set 6-3.Also advancing to the second round were seventh-seeded Xiyu Wang of China, Russia's Kamilla Rakhimova, Spain's Nuria Parrizas Diaz, Great Britain's Harriet Dart, Switzerland's Viktorija Golubic and Romania's Elena-Gabriela Ruse.--Field Level Media