Day 5 at the U.S. Open

Maria Sharapova reacts after beating Sabine Lisicki on day five of the 2014 U.S. Open.

Sabine Lisicki hits to Maria Sharapova on day five of the 2014 U.S. Open.

Andrea Petkovic returns a shot to Caroline Wozniacki on the Grandstand Court on day five of the 2014 U.S. Open tennis tournament at USTA Billie Jean King National Tennis Center.

Caroline Wozniacki during her match against Andrea Petkovic on the Grandstand Court on day five of the 2014 U.S. Open tennis tournament at USTA Billie Jean King National Tennis Center.

Venus Williams and Serena Williams during a match against Oksana Kalashnikova and Olga Savchuk in Armstrong Stadium on day five of the 2014 U.S. Open.

Sara Errani (ITA) celebrates after defeating Venus Williams.

Martin Klizan (SVK) returns a shot against Tomas Berdych (CZE).

Venus Williams (USA) returns a shot to Sara Errani (ITA).

Alize Cornet (FRA) returns a shot to Lucie Safarova (CZE).

Lucie Safarova (CZE) returns a shot to Alize Cornet (FRA).

Simona Halep (ROU) returns a shot to Mirjana Lucic-Baroni (CRO) on the Grandstand Court.

Venus Williams (USA) returns a shot to Sara Errani (ITA).

Mirjana Lucic-Baroni (CRO) returns a shot to Simona Halep (ROU) on the Grandstand Court.

Dudi Sela (ISR) returns a shot to Grigor Dimitrov (BUL).

Grigor Dimitrov (BUL) returns a shot to Dudi Sela (ISR).

Johanna Larsson (SWE) returns a shot to Jelena Jankovic (SRB).

Alejandro Gonzalez (COL) returns a shot Gael Monfils (FRA) on the Grandstand Court.

Gael Monfils (FRA) returns a shot to Alejandro Gonzalez (COL) on the Grandstand Court.

Shuai Peng (CHN) returns a shot to Roberta Vinci (ITA).