Name: Bertens advances to semis after Osaka retires
Uploaded: 2018-10-26T10:47:47.907Z
Duration: 2 min 33 s
Description: Kiki Bertens advances to the semi-finals of the WTA Finals after Naomi Osaka is forced to retire from the match due to a back injury. Reigning US Open champion Osaka called for her physio but after a brief spell was unable to continue playing.