American qualifier Vania King rallied from 4-1 down in the second set to upset fifth seed Agnes Szavay 3-6 6-4 6-3 in the second round of the Monterrey Open on Thursday.
The Hungarian seed eased into a 4-0 lead early on in Mexico and then moved to within two games of the match following two early breaks in the second set.
But King then went on the offensive and completed the comeback by saving the one break point she faced in the last set as Szavay hit five double faults.
The 20-year-old will take on Marion Bartoli in her first quarter-finals since August after the second seed beat wildcard Magdalena Rybarikova of Slovakia 6-4 6-0.
Sixth-seeded Iveta Benesova of the Czech Republic, at a career-high 31st ranking after reaching the Acapulco semi-finals last week, defeated Roberta Vinci of Italy 7-6 (7-4) 6-2.
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