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Serena Williams withdrew from the 2021 US Open on Wednesday, citing a torn hamstring. The 23-time Grand Slam singles champion initially suffered the injury during her first-round match at Wimbledon in June.

"After careful consideration and following the advice of my doctors and medical team, I have decided to withdraw from the US Open to allow my body to heal completely from a torn hamstring," she wrote on Instagram. "New York is one of the most exciting cities in the world and one of my favorite places to play -- I'll miss seeing the fans but will be cheering everyone on from afar. Thank you for your continued support and love. I'll see you soon."

In an interview with CBS Sports, Williams' coach, Patrick Mouratoglou explained the process Williams underwent to try and be tournament ready in time for the final Grand Slam of the calendar year. Ultimately, the short amount of time between when the injury was sustained (the Wimbledon women's singles tournament took place June 28 through July 10) and when the US Open is scheduled to begin (Aug. 30) did not allow for a full recovery. The risk of long-term damage was just much too great.

"[Serena] got injured at Wimbledon and we knew we had a very tight schedule to put her back on track and be able to play this US Open," Mouratoglou told CBS Sports. "We knew that any setback during this period would be a no-go. So, at the start, it went well. She started from not being able to walk to being able to be finally on a tennis court, without moving but playing tennis."

Mouratoglou said that Williams then progressed to move laterally on the courts, but after a few days, she began experiencing a lot of pain again.

"We did exams [MRI] and we realized that there was still a tear on the tendon that was not completely back to normal," Mouratoglou told CBS Sports. "Even though we tried, with one week until the US Open, we realized finally that there was a big risk with playing. The risk of a much worse injury which was really there because if you play with a tear in the tendon and you go too far, the tendon can completely break and it's something you don't want to risk."

Mouratoglou added that, in essence, it was a race against the clock.

"It's sad because it's only a question of maybe having two more weeks and she would've been fine but we didn't have those two extra weeks. She'll be completely fine [to play again] in two to three weeks but the risk was too big to take," he said.

Since Williams' return to the sport in March 2018 following the birth of her daughter, Olympia, the tennis legend had competed in every Grand Slam event that had been held. In 2021, Williams saw her best Grand Slam performance at the Australian Open in February, where she reached the semifinals before falling to eventual champion Naomi Osaka in straight sets. Williams, who turns 40 on Sept. 26, last won a Grand Slam title in January 2017 at the Australian Open when she beat her sister, Venus, in the final. 

Williams has won 23 Grand Slam singles titles in her career. The only person with more is Margaret Court, who has 24. Williams' withdrawal announcement erased the 2021 US Open's chance of being the tournament in which Williams ties Court. But that is hardly the only negative storyline heading into the event.

The 2021 US Open is lacking serious star power.

Williams' sister, Venus also announced her decision to skip the tournament due to injury, and on the men's side, both Roger Federer, 40, and Rafael Nadal, 35, have withdrawn and ended their 2021 seasons because of injuries. This year's US Open will be the first Grand Slam event without the Williams sisters, Federer and Nadal in the main singles draw since the 1996 US Open.