Serena Williams has a past of proving she can play through almost anything, including a pregnancy, and come out on top.

On Sunday (August 11), though, back spasms proved to be too painful for the 23-time grand slam champion as she was forced to retire from the Rogers Cup final during the first set.

Williams reportedly complained of the back injury then pulled out of the Toronto tournament. As she left the court, tears ran down her face.

She was joined on the sideline by her opponent, 19-year-old Bianca Andreescu, who consoled the visibly emotional tennis legend. 

"I started tearing up because she was tearing up," Andreescu said during a post-match press conference, according to CNN. "It's because I know how she feels. Injuries really, really suck."

"I’m sorry I couldn’t do it today," Williams said after 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."

The 37-year-old has been on a quest to win a grand slam title since giving birth to her daughter, Olympia, in 2017. Last month, she finished second at Wimbledon. 

Even though 2019 has been a tough year for Serena Williams on the court, she says she’s already looking ahead to her next match. "It's been a tough year, but I'm going to keep going," she said following her retirement from the Rogers Cup final.