Canadian teenager Bianca Andreescu says she "did the impossible" by beating seven-time Grand Slam champion Venus Williams a day after defeating world number three Caroline Wozniacki.
Andreescu, 18, won 11 games in a row on her way to a 6-7 (1-7) 6-1 6-3 win over Williams at the Auckland International.
Ranked 152nd, she won three qualifying matches to reach the main draw and then beat Wozniacki on Thursday.
Now she will compete in her first WTA semi-final on Saturday.
"My goal was only to qualify and maybe get a couple of rounds in but now I've beaten a couple of top players," she said.
"I believe that anything is possible and I think I did the impossible [against Williams]. It is such an amazing feeling.
Andreescu will play Taiwan's Hsieh Su-wei, who beat Spain's Sara Sorribes Tormo in their quarter-final, in the last four.