Auckland - Former World number ones Caroline Wozniacki and Venus Williams overcame spirited opposition Thursday to reach the semi-finals of the Auckland Classic.
Wozniacki, the tournament top seed, produced fighting qualities to overcome big-serving German Julia Goerges 6-4, 6-4 and set up a final four clash with Czech Barbora Zahlavova Strycova.
Third seed Williams had to come from 2-4 down in the second set to beat Russian Elena Vesnina 6-2, 6-4 and will play fellow American Lauren Davis in the semis.
Wozniacki dropped her serve once and broke back twice in a tense first set against Goerges who saved five of the seven break points she faced.
The German kept up the pressure in the second round and after breaking Wozniacki a second time, the Dane showed her anger with herself as she swatted a ball away.
After she broke back, Wozniacki later slammed her racquet on the ground when losing game point at 4-3 and 40-15 before regaining her composure for the remainder of the match.
"She serves really big and has big shots, I tried to run every ball down and even though at points I didn't feel comfortable I still just fought to the end," said Wozniacki, who was beaten by seven aces in the match.
Williams cruised through the first set against Vesnina but was made to fight when the Russian broke her early in the second.
But as the Russian's confidence grew, Williams lifted her performance to break twice in quick succession and take the match.
"Sometimes it's hard to keep the focus when you're winning, but whenever my opponent plays better I feel it raises my game," she said.
Zahlavova Strycova took nearly two hours to beat Vandeweghe with the seventh seed American blowing a chance to take the game into a third set when up 5-3 in the second.
She was broken serving for the set and then lost the next two games and the match.
Davis was taken to her third three-setter in as many games when she recovered from losing the first set to beat Polish qualifier Urszula Radwanska 2-6, 6-2, 6-1.