Bianca Andreescu has become the latest high-profile name to miss this year's US Open with the Canadian deciding against defending her women's singles title.
Andreescu defeated Serena Williams 6-3, 7-5 in last year's US Open final.
Andreescu confirmed on her social media channels that she would be joining the likes of Rafael Nadal, Ashleigh Barty and Nick Kyrgios in skipping the Slam, which will take place with no fans present and strict biosecurity protocols.
The 20-year-old, who captured her first major title against Serena Williams at the 2019 U.S. Open, says she made her decision in order to focus on her match fitness and so she can return ready to compete at her highest level.
Her decision means that this year's event, which starts in NY on August 31, will be without both of its 2019 champions after Rafael Nadal also said he would skip the tournament over health fears.
"The U.S. Open victory past year has been the high point of my career thus far and I will miss not being there", Andreescu wrote. Andreescu had previously said that she would attend the tournament.
"'Unforeseen challenges, including the Covid pandemic, have compromised my ability to prepare and compete to the degree necessary to play at my highest level", she wrote over Instagram.
"During my career, I have played some of my best matches at the USTA Billie Jean King National Tennis Center".
"I respect and appreciate everyone taking time, effort, and energy to organise these two events for the tennis players to be able to go back to their working field".
Djokovic will also compete in the Western & Southern Open, which is usually held in Cincinnati but will be played at Flushing Meadows from 22-28 August.
"It was not an easy decision to make with all the obstacles and challenges on many sides", three-time US Open victor Djokovic said.