Tamira Paszek saved five match points on her way to beating fifth seed Angelique Kerber in the final of the Eastbourne International.
The Austrian won 5-7 6-3 7-5 after almost three hours on court in the traditional warm-up event for Wimbledon.
Paszek, the world number 59, had won just two matches this season before this tournament but she put on a fierce display against the German.
Kerber had five match points while leading 5-3 in the deciding set but Paszek hung on, aided by some unforced errors from her opponent.
Paszek was left struggling with an injury after slipping during the seventh game of the decider and needed a medical time-out to have her ankle strapped and a calf massage from the trainer during a changeover before she finally sealed victory on her third match point.
The 21-year-old reached the quarter-finals at Wimbledon in 2011 but will face a tough task to repeat that feat after being drawn against former world number one Caroline Wozniacki in the first round this year.
Paszek said: "It was just an amazing feeling, I do not know what kept me going, how I kept going.
"I was dead tired in the third set. I could hardly move. I just gave all I had left, and it just was enough."