Svetlana Kuznetsova has suffered a surprise defeat to American qualifier Lauren Davis in the first round of the Rogers Cup in Toronto.
Both players struggled to hold serve during the opening set, but it was the Russian world number 28 who eventually clinched it 6-3.
Two-time Grand Slam champion Kuznetsova had the chance to serve out the match at 5-4 in the second, but the plucky Davis broke back before levelling it 7-5.
Davis, 19, powered into a 3-0 lead in the decider and was able to hold her nerve to see off Kuznetsova 7-5.
Waiting for the teenager in the next round is Wimbledon champion Marion Bartoli.