A day earlier, Pegula withdrew with a rib injury. The 30-year-old American, who went on to contest her first major singles final in New York, captured last year’s Seoul crown over Yuan Yue.
World No. 4 Elena Rybakina and No. 8 Emma Navarro have also opted out. Rybakina cited a back injury, while Navarro—making her Top 10 debut this week—noted a change in schedule.
Daria Kasatkina, Beatriz Haddad Maia and Diana Shnaider now lead the entered players. Former US Open champions Sloane Stephens and Emma Raducanu have moved into the main draw, along with American Amanda Anisimova.
