Fifth-seeded Australian Stosur ousted second-seeded Agnieszka Radwanska of Poland 7-5, 2-6, 6-3. French wild card Razzano continued her remarkable run at the USD 795,707 US Open tune-up with a 6-7 (6/8), 7-5, 7-6 (10/8) triumph over third-seeded Czech Petra Kvitova.
Razzano, who has also beaten Svetlana Kuznetsova and Spaniard Carla Suarez Navarro this week, saved two match points in the third-set tiebreaker en route to the victory.
The three-hour, 35-minute match was the second-longest on the Tour this year, behind Bethanie Mattek-Sands’ three-hour, 42-minute victory over Anastasia Rodionova at Charleston in April.
Razzano took a 5-3 lead in the third set, but let three match points slip away. Kvitova, a former Wimbledon champion, served for the match at 6-5, but Razzano broke her to force the decisive tiebreaker. Kvitova rolled to a 5-2 lead, but Razzano rallied and sealed it on her fifth match point.