No 8 seed Karolina Muchova moved into the second round of the Tokyo Open when Marketa Vondrousova retired on Monday morning at the Ariake Coliseum.
Muchova, ranked No 12, led 6-2, 1-0 when Vondrousova, ranked No 58, pulled out at the Ariake Coliseum on Monday night.
Karolina Muchova will play Australian Maya Joint next.
Tokyo WTA 500, other first-round results (Ariake Coliseum, hard, USD 1.064.510, most recent results first):
Moyuka Uchijima vs. Sofia Kenin
Wakana Sonobe vs. Nikola Bartunkova
Alina Charaeva vs. Jaqueline Cristian
Victoria Mboko vs. Bianca Andreescu
Leylah Fernandez vs. Maria Sakkari
Diana Shnaider vs. Dayana Yastremska
Anna Kalinskaya beat Suzan Lamens (LL): 6-3, 6-1
Maya Joint beat Viktorija Golubic (LL): 1-6, 7-6 (5), 6-2
McCartney Kessler beat Cristina Bucsa (Q): 3-6, 7-5, 6-3
Varvara Gracheva (Q) beat Xinyu Wang: 4-6, 6-3, 6-4
Eva Lys (Q) beat Katie Boulter (Q): 6-2, 6-1
