Serena Williams close friend and physio Esther Lee battling pancreatic cancer

Serena Williams sobs in an emotional video.

Serena Williams, a 23-time grand slam champion, broke down in tears on social media while delivering a tragic statement.

Serena Williams, the American tennis icon, broke down in tears when she revealed her close friend and physiotherapist Esther Lee was battling pancreatic cancer.

The 23-time grand slam singles winner battled to contain her emotions in a 92-second film shared to Twitter as she announced her participation in the LA Cancer Challenge 5K to help raise awareness for pancreatic cancer.

Dr Lee, who has worked as the Williams sisters' physiotherapist throughout their illustrious careers, is frequently visible courtside at their matches.

Serena Williams close friend and physio Esther Lee battling pancreatic cancer
Esther Lee and Serena Williams.

"I'm not sure I can do this; it's going to be too difficult," Williams said as she wiped away tears.

"My buddy Esther was diagnosed with pancreatic cancer last year, and she has been by my side everytime I have needed her.

My close friend Esther has been instrumental in my own health journey, and she now requires our assistance as she battles pancreatic cancer.

Esther has been named the honorary starter for the Los Angeles Cancer Challenge 5K walk-run on October 31st in UCLA, which benefits the Hirshberg Foundation for pancreatic cancer research. "My family and I have joined Team Esther to support everyone fighting this disease. "Please join us as we raise awareness and race toward a cure by finding and advancing critical research."

According to Essentially Sports, Williams once claimed she could have died in 2001 had it not been for Esther's advice to go to the hospital.

"I didn't want to go, but she said, 'You have to go,' and it was the start of some pretty horrible things that turned out to be beneficial for me," Williams recounted at the time.

"I've expressed my gratitude to her numerous times because it literally could have been life-changing."

Meanwhile, Australian tennis champion Ash Barty has withdrawn from the balance of the 2021 WTA season, including the $US14 million ($A19 million) WTA Finals.

"I wanted to communicate to everyone that I would be withdrawing from all tournaments in 2021, including the WTA Finals in Mexico," Barty stated in a statement.

"It was a difficult decision, but I need to put my body and rehabilitation from our 2021 season first and concentrate on having the strongest pre-season possible for the Australian summer."

With the continued difficulties associated with returning to Queensland and meeting quarantine regulations, I am unwilling to jeopardize my preparations for January."

"I wish the WTA team and players the best of luck for the WTA Finals and the remainder of the year. "My emphasis is now on the Australian summer and doing all possible to win the Australian Open. I'm very excited to be able to play at home again."