Katie Boulter, the British No.1, has progressed to the third round of the National Bank Open in Toronto after Beatriz Haddad Maia was forced to retire with a back problem.
Brazilian Haddad Maia had come through a marathon first-round match against Marie Bouzkova – which lasted three hours and 20 minutes – but was soon calling for the trainer after the opening game against Boulter.
The world No.33 received lengthy treatment on her lower back and although she tried to resume, Haddad Maia swiftly conceded after Boulter, who beat Bernarda Pera in the first round, levelled the set at 1-1.
Boulter, who is in a relationship with Australian tennis star Alex de Minaur, will go on to face the winner of Aryna Sabalenka, the world No.3, and China’s Yuan Yue for a place in the quarter-finals.
Elsewhere on Thursday, top seed Coco Gauff comfortably beat Wang Yafan 6-4 6-4 in her second-round match.