Caroline Wozniacki faces Serena Williams in the U.S. Open final . Wozniacki advances in dramatic fashion after her opponent retired . The world No. 1 will play a rematch against former champion Venus Williams, who beat her at Roland Garros last year. World No . 1 Williams crushed Russia 's Ekaterina Makarova in an hour .
Caroline Wozniacki faces Serena Williams in the U.S. Open final . Wozniacki advances in dramatic fashion after her opponent retired . China 's Peng Shuai had to be taken off center court in a wheelchair . World No . 1 Williams crushed Russia 's Ekaterina Makarova in an hour .