Serena & Venus Williams at the Olympics

Williams sisters Venus and Serena compete for gold at the All-England Club in London during the Olympics.

Tennis - Australian Open - Melbourne Park, Melbourne, Australia

Serena Williams of the U.S. hits a shot during her Women's singles final match against Venus Williams of the U.S. .REUTERS/Thomas Peter

Tennis - Australian Open - Melbourne Park, Melbourne, Australia

Tennis - Australian Open - Melbourne Park, Melbourne, Australia - 28/1/17 Serena Williams of the U.S. serves during her Women's singles final match against Venus Williams of the U.S. .REUTERS/Edgar Su

Tennis: U.S. Open

Sept 1, 2016; New York, NY, USA; Serena Williams of the USA hits to Vania King of USA (not pictured) on day four of the 2016 U.S. Open tennis tournament at USTA Billie Jean King National Tennis Center. Mandatory Credit: Robert Deutsch-USA TODAY Sports / Reuters Picture Supplied by Action Images

FILE PHOTO: Tennis - Australian Open - Melbourne Park, Melbourne, Australia

FILE PHOTO: Tennis - Australian Open - Melbourne Park, Melbourne, Australia - 28/1/17 Serena Williams of the U.S. hits a shot during her Women's singles final match against Venus Williams of the U.S. REUTERS/Thomas Peter/File Photo

FILE PHOTO: Tennis - Australian Open - Melbourne Park, Melbourne, Australia

FILE PHOTO: Tennis - Australian Open - Melbourne Park, Melbourne, Australia - 28/1/17 Serena Williams of the U.S. hits a shot during her Women's singles final match against Venus Williams of the U.S. REUTERS/Thomas Peter/File Photo

BRITAIN'S FORMER PRIME MINISTER HEATH WATCHES WOMEN'S SINGLES FINAL AT WIMBLEDON.

Britain's former Prime Minister Sir Edward Heath watches the women's singles final match between Serena and Venus Williams of the U.S. on centre court at the Wimbledon Tennis Championships in London, July 5, 2003. PP05070202 REUTERS/Ian Hodgson

Wimbledon

FILE PHOTO - Tennis - Wimbledon - London, Britain - July 11, 2017 Latvia’s Jelena Ostapenko in action during her quarter final match against Venus Williams of the U.S. REUTERS/Tony O'Brien

Metropolitan Museum of Art Costume Institute Gala - Rei Kawakubo/Comme des Garcons: Art of the In-Between - Arrivals

Serena Williams. REUTERS/Lucas Jackson

Serena Williams of the U.S. reacts next to her coach Patrick Mouratoglou during a training session ahead of the Australian Open tennis tournament in Melbourne

FILE PHOTO: Serena Williams of the U.S. reacts next to her coach Patrick Mouratoglou during a training session ahead of the Australian Open tennis tournament in Melbourne, Australia, January 15, 2017. REUTERS/Edgar Su

Serena Williams of the U.S. reacts next to her coach Patrick Mouratoglou during a training session ahead of the Australian Open tennis tournament in Melbourne

FILE PHOTO: Serena Williams of the U.S. reacts next to her coach Patrick Mouratoglou during a training session ahead of the Australian Open tennis tournament in Melbourne, Australia, January 15, 2017. REUTERS/Edgar Su

Serena Williams of the US sits on her racquet as she talks to her coach Patrick Mouratoglou during a practice session at Melbourne Park, Australia

FILE PHOTO: Serena Williams (R) of the U.S. sits on her racquet as she talks to her coach Patrick Mouratoglou during a practice session at Melbourne Park, Australia, January 14, 2016. The Australian Open tennis tournament starts January 18. REUTERS/David Gray

Tennis - French Open Womens Singles Semifinal match - Roland Garros - Serena Williams of the US vs Kiki Bertens of the Netherlands

FILE PHOTO: Tennis - French Open Womens Singles Semifinal match - Roland Garros - Serena Williams of the U.S. vs Kiki Bertens of the Netherlands - Paris, France - 03/06/16. Patrick Mouratoglou, coach of Serena Williams. REUTERS/Benoit Tessier

Patrick Mouratoglou, coach and boyfriend of Serena Williams of the U.S., attends her match against Li Na of China at the U.S. Open tennis championships in New York

Patrick Mouratoglou, coach and boyfriend of Serena Williams of the U.S., attends her match against Li Na of China at the U.S. Open tennis championships in New York September 6, 2013. REUTERS/Eduardo Munoz/Files

Wimbledon

FILE PHOTO: Tennis - Wimbledon - London, Britain - July 13, 2017 Great Britain’s Johanna Konta in action during her semi final match against Venus Williams of the U.S. REUTERS/Alastair Grant/Pool

Wimbledon

FILE PHOTO: Tennis - Wimbledon - London, Britain - July 13, 2017 Great Britain’s Johanna Konta in action during her semi final match against Venus Williams of the U.S. REUTERS/Alastair Grant/Pool

FILE PHOTO: Tennis - Australian Open - Melbourne Park, Melbourne, Australia

FILE PHOTO: Tennis - Australian Open - Melbourne Park, Melbourne, Australia - 28/1/17 Serena Williams of the U.S. hits a shot during her Women's singles final match against Venus Williams of the U.S. .REUTERS/Thomas Peter/File Photo

Wimbledon

Tennis - Wimbledon - London, Britain - July 13, 2017 Great Britain’s Johanna Konta in action during her semi final match against Venus Williams of the U.S. REUTERS/Alastair Grant/Pool

Wimbledon

FILE PHOTO: China’s Qiang Wang in action during her second round match against USA’s Venus Williams at Wimbledon, London July 5, 2017 REUTERS/Matthew Childs

Wimbledon

FILE PHOTO: China’s Qiang Wang in action during her second round match against USA’s Venus Williams at Wimbledon, London July 5, 2017 REUTERS/Matthew Childs

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location, September 13, 2017 in this picture obtained from a social media. INSTAGRAM/ SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT.NO RESALES. NO ARCHIVES TPX IMAGES OF THE DAY

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location in this still image taken from an undated social media video on September 13, 2017. YOUTUBE / SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location in this still image taken from an undated social media video on September 13, 2017. YOUTUBE / SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location in this still image taken from an undated social media video on September 13, 2017. YOUTUBE / SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location, September 13, 2017 in this picture obtained from a social media. INSTAGRAM/ SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location, September 13, 2017 in this picture obtained from a social media. INSTAGRAM/ SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location in this still image taken from an undated social media video on September 13, 2017. YOUTUBE / SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT.NO RESALES. NO ARCHIVES

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams is seen with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location in this still image taken from an undated social media video on September 13, 2017. YOUTUBE / SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT.NO RESALES. NO ARCHIVES

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location, September 13, 2017 in this picture obtained from a social media. INSTAGRAM/ SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location, September 13, 2017 in this picture obtained from a social media. INSTAGRAM/ SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location

Tennis player Serena Williams poses with her daughter Alexis Olympia Ohanian Jr. in an undisclosed location, September 13, 2017 in this picture obtained from a social media. INSTAGRAM/ SERENA WILLIAMS / ALEXIS OHANIAN/ via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT.NO RESALES. NO ARCHIVES

Serena Williams of the U.S. attends a news conference ahead of the Australian Open tennis tournament in Melbourne

Serena Williams of the U.S. attends a news conference in Melbourne, Australia, January 14, 2017. REUTERS/Edgar Su

Metropolitan Museum of Art Costume Institute Gala - Rei Kawakubo/Comme des Garcons: Art of the In-Between - Arrivals

Metropolitan Museum of Art Costume Institute Gala - Rei Kawakubo/Comme des Garcons: Art of the In-Between - Arrivals - New York City, U.S. - 01/05/17 - Serena Williams. REUTERS/Lucas Jackson

Metropolitan Museum of Art Costume Institute Gala - Rei Kawakubo/Comme des Garcons: Art of the In-Between - Arrivals

Metropolitan Museum of Art Costume Institute Gala - Rei Kawakubo/Comme des Garcons: Art of the In-Between - Arrivals - New York City, U.S. - 01/05/17 - Serena Williams. REUTERS/Lucas Jackson

Metropolitan Museum of Art Costume Institute Gala - Rei Kawakubo/Comme des Garcons: Art of the In-Between - Arrivals

Metropolitan Museum of Art Costume Institute Gala - Rei Kawakubo/Comme des Garcons: Art of the In-Between - Arrivals - New York City, U.S. - 01/05/17 - Serena Williams. REUTERS/Lucas Jackson

Tennis: U.S. Open

Sep 7, 2017; New York, NY, USA; Sloane Stephens of the United States celebrates after match point against Venus Williams of the United States (not pictured) on day eleven of the U.S. Open tennis tournament at USTA Billie Jean King National Tennis Center. Mandatory Credit: Geoff Burke-USA TODAY Sports

FILE PHOTO - Tennis: U.S. Open

FILE PHOTO - Sept 7 2017; New York, NY, USA; Sloane Stephens of the USA hits to Venus Williams of the USA in Ashe Stadium at the USTA Billie Jean King National Tennis Center. Mandatory Credit: Robert Deutsch-USA TODAY Sports

FILE PHOTO - Tennis: U.S. Open

FILE PHOTO - Sep 7, 2017; New York, NY, USA; Sloane Stephens of the United States serves to Venus Williams of the United States on day eleven of the U.S. Open tennis tournament at USTA Billie Jean King National Tennis Center. Mandatory Credit: Anthony Gruppuso-USA TODAY Sports

Tennis - US Open

Tennis - US Open - Semifinals - New York, U.S. - September 7, 2017 - Sloane Stephens of the United States reacts after defeating Venus Williams of the United States. REUTERS/Mike Segar