Three years ago, Tiger Woods defied doctor's orders to compete in the US Open at Torrey Pines where he stunningly triumphed in a playoff after enduring intense knee pain throughout the tournament.

Since that unforgettable day on the Californian coastline, Woods has suffered further injury problems and, with the 2011 US Open set for next week, he has decided to follow medical advice and will not compete in the year's second major.

It will be the first US Open he has missed since 1994, when he had just graduated from high school, and the mere thought of skipping one of golf's elite events would have left a very bitter taste in his mouth.

However, Woods accepts that short-term disappointment must be the sacrifice for possible long-term gain and, with his mind and heart still firmly set on acquiring more major titles, this was the only realistic option available to him.

"It's time for me to listen to my doctors and focus on the future," the American former world No 1 said on his website on Tuesday when he ruled himself out of the US Open.

"I was hopeful that I could play, but if I did, I risk further damage to my left leg. My knee and Achilles tendon are not fully healed."

Woods hurt his left knee and Achilles tendon during the Masters in April when he tied for fourth. He has since played only nine more holes in competition before having to withdraw from the Players Championship in May because of injury.

The 14-time major champion, whose 200-kph swing is among the fastest on the PGA Tour, has long been aware of the vulnerability of his left knee.

When striving for extra distance in the past, he often tended to snap his left leg straight just before impact, a move he has since worked hard to alleviate by remodeling his swing and sacrificing yards off the tee.

"Golf puts tremendous stresses on your knee, your upper extremities and especially your back," sports medicine surgeon Dr Robert Frederick said. "And golfers are particularly prone to over-use injuries from the repeated stresses that the body sustains.

"Achilles tendinopathy, or inflammation of the Achilles' tendon, could rear its ugly head for Tiger on a repeated basis depending on how hard he pushes it.

"But the main thing I would be concerned about is his knee because of the multiple surgeries he has had in the past," said Frederick, who is a doctor at the Rothman Institute at Thomas Jefferson University Hospital in Philadelphia.

"If the arthritis (in the knee) is too severe, activity modifications, including diminishing time on the golf course, may be things that have to be included."

Injury setbacks

Aged only 35, Woods has already had four surgeries on his troublesome left knee and his latest injury setback raises doubts about how soon he will be able to return to regular practise and competition.

He has targeted the PGA Tour's AT&T National from June 30-July 3 for a possible comeback with his sights firmly set on playing the last two majors of the year - the British Open and the PGA Championship.

The majors have always been the overriding goal for Woods, who has targeted the record 18 won by fellow American Jack Nicklaus.

However, he has been unable to add any more to his own trophy cabinet since the 2008 US Open and his absence from next week's championship at Congressional in Bethesda, Maryland, will mark his 12th consecutive major without a victory.

Comfortably the best player of his generation and arguably of all time, Woods has slipped to 15th in the world rankings with six Americans above him and has not won a tournament since the 2009 Australian Masters.

Nicklaus, more than anyone else, knows all about the need to stay fit in the pursuit of winning majors and he feels Woods is not helped by the extra 'violent' modern-day swing.

"Tiger's swing, and a lot of the swings of today, are far more violent at the ball than some of the old swings," Nicklaus said before last week's Memorial tournament, which he hosts.

"Some of the old swings were far more rhythmic. The game today is far more an upper-body game, and we used to play more from the ground up."

Although Woods is working on the fourth swing change of his professional career, Nicklaus believes many of the fundamentals will remain the same.