The fifth seed, Jamie Hampton, is through to the Auckland tennis Classic semi-finals, after beating her American compatriot Lauren Davis in a hard-fought 6-2, 4-6, 6-4 win.
While Hampton eased through the first set without too much trouble, her 20-year-old opponent found her stride in the second set, and forced the world number 28 into some silly errors, including four double faults.
Davis kept up the pressure in the third, but Hampton's experience won through in the end, as she held her nerve to take the final set.
Hampton is ranked 42 places higher than Davis, but the pair do train with each other when back at the United States, so know each other's games quite well.
Hampton will meet Venus Williams in the other semi-final after the American great knocked out Spaniard Garbine Muguruza.