“I’m sorry I couldn’t do it today,” Williams said following the match. “I tried, but I couldn’t. Bianca, you’re a great sportswoman. It’s been a tough year but I’m going to keep going.”

Thanks to her defeat of Williams, Andreescu became the first Canadian to win the Rogers Cup since 1969.

During the post-game press conference, Williams referred to Andreescu as “fabulous” and “an old soul.”

“My whole back spasmed to the point where I couldn’t see,” Williams explained. “I couldn’t really move.”

• Wimbledon: Simona Halep Defeats Serena Williams

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  LONDON, ENGLAND - JULY 13: Serena Williams of The United States plays a backhand in her Ladies' Singles final against Simona Halep of Romania during Day twelve of The Championships - Wimbledon 2019 at All England Lawn Tennis and Croquet Club on July 13, 2019 in London, England. (Photo by Laurence Griffiths/Getty Images)

• Wimbledon: Simona Halep Defeats Serena Williams

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  LONDON, ENGLAND - JULY 13: Serena Williams of The United States serves in her Ladies' Singles final against Simona Halep of Romania during Day twelve of The Championships - Wimbledon 2019 at All England Lawn Tennis and Croquet Club on July 13, 2019 in London, England. (Photo by Laurence Griffiths/Getty Images)

• Wimbledon: Simona Halep Defeats Serena Williams

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  LONDON, ENGLAND - JULY 13: Serena Williams of The United States plays a forehand in her Ladies' Singles final against Simona Halep of Romania during Day twelve of The Championships - Wimbledon 2019 at All England Lawn Tennis and Croquet Club on July 13, 2019 in London, England. (Photo by Laurence Griffiths/Getty Images)
• Wimbledon: Simona Halep Defeats Serena Williams

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  LONDON, ENGLAND - JULY 13: Serena Williams of The United States serves in her Ladies' Singles final against Simona Halep of Romania during Day twelve of The Championships - Wimbledon 2019 at All England Lawn Tennis and Croquet Club on July 13, 2019 in London, England. (Photo by Laurence Griffiths/Getty Images)

• Wimbledon: Simona Halep Defeats Serena Williams

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  LONDON, ENGLAND - JULY 13: Serena Williams of The United States and Simona Halep of Romania embrace after their Ladies' Singles final during Day twelve of The Championships - Wimbledon 2019 at All England Lawn Tennis and Croquet Club on July 13, 2019 in London, England. (Photo by Laurence Griffiths/Getty Images)

• 2019 French Open – Day Two

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  PARIS, FRANCE - MAY 27: Serena Williams of The United States reacts during her ladies singles first round match against Vitalia Diatchenko of Russia during Day two of the 2019 French Open at Roland Garros on May 27, 2019 in Paris, France. (Photo by Adam Pretty/Getty Images)
• SERENA WILLIAMS

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• Serena Williams at the 2019 Met Gala

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  NEW YORK, NEW YORK - MAY 06: Serena Williams attends The 2019 Met Gala Celebrating Camp: Notes on Fashion at Metropolitan Museum of Art on May 06, 2019 in New York City. (Photo by Dimitrios Kambouris/Getty Images for The Met Museum/Vogue)

• Serena Williams

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  BEVERLY HILLS, CA - FEBRUARY 24: Serena Williams attends the 2019 Vanity Fair Oscar Party hosted by Radhika Jones at Wallis Annenberg Center for the Performing Arts on February 24, 2019 in Beverly Hills, California. (Photo by Dia Dipasupil/Getty Images)
• Serena Williams

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  HOLLYWOOD, CALIFORNIA - FEBRUARY 24: Serena Williams attends the 91st Annual Academy Awards at Hollywood and Highland on February 24, 2019 in Hollywood, California. (Photo by Frazer Harrison/Getty Images)

• The Premiere Of EPIX Original Documentary “Serena” – Arrivals

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  NEW YORK, NY - JUNE 13: Serena Williams attends the Premiere Of EPIX Original Documentary "Serena" at SVA Theatre on June 13, 2016 in New York City. (Photo by Jamie McCarthy/Getty Images)

• Prince Harry Marries Ms. Meghan Markle – Windsor Castle

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  WINDSOR, UNITED KINGDOM - MAY 19: Serena Williams arrives at St George's Chapel at Windsor Castle before the wedding of Prince Harry to Meghan Markle on May 19, 2018 in Windsor, England. (Photo by Gareth Fuller - WPA Pool/Getty Images)
• Prince Harry Marries Ms. Meghan Markle – Windsor Castle

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  WINDSOR, ENGLAND - MAY 19: Serena Williams and Alexis Ohanian attend the wedding of Prince Harry to Ms Meghan Markle at St George's Chapel, Windsor Castle on May 19, 2018 in Windsor, England. Prince Henry Charles Albert David of Wales marries Ms. Meghan Markle in a service at St George's Chapel inside the grounds of Windsor Castle. Among the guests were 2200 members of the public, the royal family and Ms. Markle's Mother Doria Ragland. (Photo by Shaun Botterill/Getty Images)

• Mubadala World Tennis Championship – Day Three

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  Serena Williams (Photo by Tom Dulat/Getty Images)

• “Rei Kawakubo/Comme des Garcons: Art Of The In-Between” Costume Institute Gala – Arrivals

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  NEW YORK, NY - MAY 01: Serena Williams attends the "Rei Kawakubo/Comme des Garcons: Art Of The In-Between" Costume Institute Gala at Metropolitan Museum of Art on May 1, 2017 in New York City. (Photo by Dia Dipasupil/Getty Images For Entertainment Weekly)
• “Rei Kawakubo/Comme des Garcons: Art Of The In-Between” Costume Institute Gala – Arrivals

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  NEW YORK, NY - MAY 01: Serena Williams attends the "Rei Kawakubo/Comme des Garcons: Art Of The In-Between" Costume Institute Gala at Metropolitan Museum of Art on May 1, 2017 in New York City.

• Day Twelve: The Championships – Wimbledon 2016

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  Venus Williams and Serena Williams (Photo by Clive Brunskill/Getty Images)

• 2015 U.S. Open – Day 9

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  NEW YORK, NY - SEPTEMBER 08: Serena Williams (L) of the United States hugs Venus Williams of the United States after defeating her in their Women's Singles Quarterfinals match on Day Nine of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 8, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Al Bello/Getty Images)