• Russian retires from match against Kristina Liutova

• Venus Williams and Katie Boulter beaten in Washington

Ekaterina Alexandrova collapsed on the court before retiring from her match against Kristina Liutova at the Memphis Classic due to heat-related illness.

Alexandrova, the tournament’s No 1 seed, was two points away from defeat to the 16-year-old Liutova, who was making her WTA Tour debut. The temperature was around 97F (36C) in Tennessee as the two Russians played out a gruelling first-round match ​lasting more than three hours.