Lauren Davis saved eight match points before booking her place in the quarter-finals of the Aegon Open.
The American prevailed in a three-set battle against Magda Linette, winning 5-7 7-6 (15/13) 6-2 in a contest which lasted nearly three hours.
Davis, 21, told the ATP's official website afterwards: "I had eight match points against me, which is really insane, but I never stopped believing and tried to stay in the moment.
"I believed in myself, I believed I could win - and that fighting spirit just comes naturally to me."
Joining Davis in the last eight is compatriot Alison Riske, who progressed in straight sets.
The number five seed won 6-3 6-4 against Mirjana Lucic-Baroni and was full of praise for the grass courts at Nottingham Tennis Centre.
Riske said: "I think every year I've come here, the courts have been fantastic. It plays very well - it's as good a grass court as I've ever played on."
Source: PA
