Serena Williams and Bianca Andreescu will not compete in the upcoming 2022 Australian swing.

Seven-time champion Williams, 40, was not on the Australian Open entry list, released on Wednesday. Her withdrawal was due to advice from her medical team, she said in a statement.

"While this is never an easy decision to make, I am not where I need to be physically to compete," she said.

"Melbourne is one of my favorite cities to visit and I look forward to playing at the AO every year. I will miss seeing the fans, but am excited to return and compete at my highest level."

Williams was a semifinalist in 2021, defeating Aryna Sabalenka and Simona Halep before falling to eventual champion Naomi Osaka. A left knee injury sidelined her until the clay season this year. The 23-time Grand Slam winner reached the fourth round of Roland Garros, but has not competed since an ankle injury forced her to retire six games into her first-round Wimbledon clash with Aliaksandra Sasnovich. She is currently ranked World No.41.

Williams's last title came at Auckland in 2020.

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On Tuesday, former US Open champion Andreescu explained her decision on Twitter.  

"Hi everyone. As you all know, the last two years have been very challenging for me for a variety of reasons," Andreescu wrote. "Especially this year in particular, I spent multiple weeks in isolation quarantining, which affected me greatly - both mentally and physically. In addition, my grandmother spent several weeks in the ICU for a COVID infection, something that really hit me hard.

"A lot of days, I did not feel like myself, especially while I was training and/or playing matches. I felt like I was carrying the world on my shoulders. I could not detach myself from everything that was going on off the court; was feeling the collective sadness and turmoil around and it took its toll on me. 

"I want to give myself extra time to re-set, recover, and grow from this [as cliche as that sounds] and continue to inspire by doing charity work, giving back and working on myself because I know by doing this, I will come back stronger than ever. 

"I will therefore not start my season in Australia this year, but will take some additional time to reflect, train, and be ready for the upcoming 2022 tennis season."

Andreescu, the 2019 US Open champion, finished her 2021 season ranked No.46. After sitting out the 2020 season due to injury, Andreescu, a former World No.4, played her first match in more than a year at the Australian Open in February. Less than two months later, she was into a WTA 1000 final at the Miami Open, where she tallied wins over Garbiñe Muguruza and Maria Sakkari before retiring in the final against No.1 Ashleigh Barty. 

Andreescu, 21, would make one quarterfinal for the rest of the season. She announced a split with coach Sylvain Bruneau in June and brought on veteran coach Sven Groeneveld ahead of the summer hardcourt season. The new pairing yielded a solid Round of 16 showing at the US Open. Andreescu finished her 2021 campaign with a third-round loss to Anett Kontaveit at Indian Wells.