Going back to a first-round exit at the 2003 Australian Open in her very first Grand Slam tournament, Maria Sharapova never has missed one of tennis' major championships.

She will now.

Sharapova is skipping the U.S. Open because of a torn rotator cuff tendon in her right shoulder, the same injury that is forcing her to sit out the Beijing Olympics.

The three-time Grand Slam title winner said in a posting on her Web site yesterday she probably won't need surgery and could be ready to play in two to three months.

"It hurts me so much to miss the Olympics and the U.S. Open, you have no idea," she said. "Just to type those words hurt!!"

In a sport that often sees top players sidelined by injury, the No. 3-ranked Sharapova has played in each of the past 23 major tournaments, winning championships at Wimbledon in 2004, the U.S. Open in 2006 and the Australian Open in January.

She would have been counted among the main contenders at this year's U.S. Open, which begins in New York on Aug. 25.

But a doctor who looked at tests on her shoulder from April and this week told Sharapova she has been playing with that tendon tear in her shoulder since the spring.

"He actually couldn't believe that I've been playing this long with this injury. You can imagine that I was not very thrilled to hear that my medical team did not see this tear in my shoulder back in April," she said. "The good news is that it didn't get much worse since April, but we could have started the healing time back then instead of now."

Sharapova will go to Arizona to work with a specialist for rehab and strength work.

"Now I need to move forward and stay positive," she said. "I am going to work hard to get healthy."

Sharapova is 32-4 with three titles in 2008, and she briefly was ranked No. 1. The 21-year-old Russian has become one of tennis' biggest stars, with millions of dollars in endorsement deals.

She pulled out of a tournament in Montreal because of the shoulder on Wednesday night — after winning a nearly three-hour match in which she double-faulted 17 times. Sharapova then had a series of tests on her shoulder and said Thursday she wouldn't compete in Beijing.

"Once I'm healthy, I'm sure I'll look at this as a blessing in disguise," she said Friday. "Right now it's a bit painful, of course, but every athlete goes through these patches and I'm just grateful that this isn't as bad as it could have been."