Host country favorite Naomi Osaka advanced to the second round of the Pan Pacific Open on Tuesday as her Australian opponent Daria Saville had to retire early in the first set with a leg injury.
Saville fell to the court in pain after hitting a forehand in her first service game at Tokyo's Ariake tennis park. It happened after defending champion but unseeded Osaka, ranked 48th in the world, held her serve in the opening game.
The tournament has been held for the first time since 2019 following a two-year COVID-19 hiatus.
Earlier in the day, fifth-seeded Brazilian Beatriz Haddad Maia defeated Japan's Yuki Naito 6-4, 6-2.
Sixth-seeded Czech Karolina Pliskova cruised to a 6-2, 6-1 victory over Isabella Shinikova of Bulgaria.