Maria Sharapova, ranked No. 3 in the world and the No. 2 seed at the upcoming U.S. Open, withdrew from the Grand Slam tournament on Sunday due to a right leg injury. The 28-year-old Russian had not competed in a tournament since July when she reached the semifinals at Wimbledon, falling to top-ranked Serena Williams in straight sets.

"Unfortunately I will not be able to compete in this years US Open," Sharapova posted on her Facebook page. "I have done everything possible to be ready but it was just not enough time. To all my amazing fans, I will be back in the Asian swing in a few weeks and look forward to finishing the year healthy and strong."

Sharapova's inactivity in August made her questionable for the U.S. Open, particularly after pulling out of the Rogers Cup in Toronto a week before the tournament.

She had previously told the WTA official website that she had been "back on the court a little bit" though not as much as she had liked. Sharapova described her condition as "still a day-to-day thing." On Friday, she posted a picture of herself serving on Twitter with the caption, "How beautiful is the new Arthur Ashe Roof at night?" 

The five-time major champion was a 9/1 favorite to win in New York, trailing Williams (5/6) and Victoria Azarenka (8/1). In 2015, she has a 34-7 record, with an appearance in the Australian Open final, and a fourth-round finish at the French Open. The last time Sharapova won a U.S. Open title was 2006, and her last Grand Slam title was at the 2014 French Open.

According to the USTA, 18-year-old Russian Daria Kasatkina will replace Sharapova in the main draw. The U.S. Open begins on Monday.