Great Britain's Johanna Konta has secured a quarter-final showdown with Angelique Kerber after coming through a marathon clash with Svetlana Kuznetsova.
The 25-year-old looked to be heading out of the Olympic Games after losing the first set to the experienced Russian but she fought back in the second to force a decider.
After a lengthy break before the third, Konta established a 5-3 lead but she failed to serve out the match as Kuznetsova threatened to deny the world number 13 a place in the last eight.
However, after seeing three match points pass her by, Konta converted on the fourth to seal a 3-6 7-5 7-5 victory in three hours and seven minutes.
She will play Australian Open champion Kerber for a place in the semi-finals after the German beat Samantha Stosur by a 6-0 7-5 scoreline.