(CNN) -- Top-ranked tennis superstar Serena Williams said a foot injury that forced her to pull out of the U.S. Open is "devastating."
"Playing in front of the electric crowd of New York at the U.S. Open and competing against the best female athletes in the world is always a highlight, and I look forward to getting back on the court as quickly as possible," Williams said in a statement Friday.
Williams' doctors advised her against playing at the tournament, which begins August 30. She has been recovering from recent surgery on her cut right foot.
"I take great pride in playing the Grand Slam tournaments and have not missed one since 2006. Not being able to be part of this year's U.S. Open is one of the most devastating moments of my career," Williams said.
Williams, 28, has won at least one singles title in all four Grand Slam tournaments -- 13 in all -- including three U.S. Opens. She won this year's Australian Open and Wimbledon singles titles.
She went into a tirade against a line judge over a questionable call at the 2009 U.S. Open. Williams later issued an apology.
Kim Clijsters, who beat Williams last year in that semifinal, has suffered a blow in her preparations to defend her title at Flushing Meadows.
The Belgian was hampered by a hip injury as she was beaten in the quarterfinals of the Rogers Cup in Toronto on Friday.
The fifth seed lost 2-6 6-3 6-2 to Russian No. 8 Vera Zvonareva, who followed up her win over the former world No. 1 at the same stage at Wimbledon in July.
Clijsters will now have a scan on her hip to determine the extent of the problem.
"It gradually got tighter and tighter. I was still able to move and hit the ball, so I don't believe in giving up. I'll take a few days, a lot of treatment, stretches and make sure it's all relaxed," she told the WTA Tour website.
Zvonareva will next face 10th seed Victoria Azarenka in the last four after the Belarusian beat French No. 17 Marion Bartoli 6-2 7-6 (8-6).
Saturday's other semifinal at the Canadian hardcourt event is between world No. 2 Caroline Wozniacki and 11th seed Svetlana Kuznetsova.
Wozniacki, last year's losing U.S. Open finalist, avenged her defeat by Italian sixth seed Francesca Schiavone at the French Open by beating the Paris champion 6-2 6-3.
Kuznetsova, the 2004 U.S. Open champion, was similarly dominant against China's Zheng Jie, with the Russian winning 6-1 6-3.