Serena Williams faces Italian Roberta Vinci and Halep comes up against Flavia Pennetta
Simona Halep
Halep was truly gutsy knocking off the former No. 1 Victoria Azarenka, going for her shots deep into the third set. 
Victoria Azarenka
The Italian Pennetta went to the wall against Petra Kvitova, rallying to win in three sets. The two faster players won, tripping up the stronger competitors, and now Halep and Pennetta will go at each other, toe to toe, to see who can advance to their first US Open final.
