The announcement, which Woods made Tuesday night on his Web site, was a surprise to everyone except those around him.
"He's been having a lot of trouble," swing coach Hank Haney said. "He doesn't talk about stuff like that. He doesn't want to use excuses, you know? I don't think it affected his play. It affected his practice a little bit."
Tuesday's surgery was performed in Park City, Utah, by Thomas Rosenberg, who also operated on Woods' left knee in December 2002. Woods also had surgery in 1994 on his left knee to remove a benign tumor.
"I made the decision to deal with the pain and schedule the surgery for after the Masters," Woods said on his Web site. "The upside is that I have been through this process before and know how to handle it. I look forward to working through the rehabilitation process and getting back to action as quickly as I can."
But he will not be able to defend his title in two weeks at the Wachovia Championship. And he most likely will miss The Players Championship the week after, one of only three non-majors he has never missed since turning pro. Provided rehab goes as expected, Woods hopes to return at the Memorial on May 29.
The U.S. Open begins June 12 at Torrey Pines, where Woods has won six times ind PGA Championship in consecutive weeks, then tied for second behind Phil Mickelson at the Deutsche Bank Championship. That was his last loss until late March, the longest winning streak of his career, which covered five PGA Tour events, the Dubai Desert Classic on the European Tour, and his unofficial Target World Challenge in December.
"I knew he was going to do something this year," Haney said, referring to surgery. "I just didn't know when."
Woods has a remarkable track record when returning from a long layoff. After the '02 surgery, he won three of his first four events, including an 11-shot victory at Bay Hill.
This will be the second time in two years, however, that he missed a chunk of time between the Masters and the U.S. Open. He sat out nine weeks in 2006 to cope with the May death of his father, not returning until the U.S. Open at Winged Foot. He missed the cut for the only time in a major since he turned pro.
Torrey Pines is more familiar turf, even if the setup for the U.S. Open will be vastly different. Woods won the Buick Invitational this year for the third straight time, and he also won there as a junior.
In the meantime, his absence is a blow to the Wachovia Championship and to The Players Championship, regarded as the fifth major.
"Of course, we're disappointed when Tiger is unable to compete in a PGA Tour event," commissioner Tim Finchem said on the tour's Web site. "There is really never a good time for an athlete -- especially one of Tiger's caliber -- to take weeks off from competition during the season. But his health concerns have to come first."