Watching Tiger Woods up close on the 4th hole at Torrey Pines near San Diego on Sunday, it was hard to imagine him finishing the final round of the US Open. Not for the first time in four days, the world No 1 had been doubled over in pain after his drive off the tee, but this time he looked in such distress that the doubts were etched upon even his face.

And no wonder. Yesterday, speaking in Munich, Paul Casey provided the most graphic description of the injury, based on a conversation he had had with the caddie of Robert Karlsson, the Swede who played alongside Woods in the third round. “He [Gareth Lord] said there were actually noises coming from Tiger's knee,” Casey said. “Clearly he was suffering. There was a moment where Tiger, I think at the 18th, stepped up to hit his tee-shot and backed off because of weird noises. They all chuckled and he said, 'I shouldn't hit this one too hard.' He got it in play and made eagle. Hopefully he hasn't done himself any further damage.”

In a statement on his website yesterday Woods explained that he will undergo reconstructive surgery to repair the anterior cruciate ligament in his left knee. Not only that, but he has a double stress fracture (cracks) of his tibia - the shinbone - that is going to require considerable rest. If a fracture occurs in or around a joint, which is likely to be the case here, there is a high risk of developing arthritis. The stress fractures were attributed, Woods said, to “intense rehabilitation and preparations for the US Open”.

From the time Woods announced after the Masters ten weeks ago that he was about to have arthroscopic surgery to remove damaged cartilage from around the joint, there has been speculation about the extent of the injury. After all, this was his third operation on the joint. In 1994 he had a benign tumour removed and, eight years later he had cysts cut away and the knee drained of fluid.

Woods originally ruptured the anterior cruciate ligament, when he was running near his home in Orlando, Florida, after the Open Championship at Carnoustie last year. He chose not to have surgery and decided to play through the pain. The knock-on effect was damage to the cartilage and further damage to the ligament. If such ligaments are torn, they will not heal.

Reconstruction involves the grafting of “harvested” ligament from the patient - either from the hamstring or the patella tendon that connects the knee cap to the shinbone. Alternatively, many procedures take donor tissue from a cadaver. Recovery time should be at least six months and full recovery from this type of operation is not guaranteed.

After his victory in a 19-hole play-off against Rocco Mediate on Monday, Woods said with a simple nod of the head that doctors had warned him that by playing on there could be long-term repercussions.

Yesterday was time for reflection. “Now it is clear that the right thing to do is to listen to my doctors, follow through with this surgery and focus my attention on rehabilitating my knee,” he said. “My doctors assure me with the proper rehabilitation and training, there will be no long-term effects.”

Other sporting giants who have succumbed to anterior cruciate ligament injuries

RUGBY: Lawrence Dallaglio

Lawrence Dallaglio ruptured his anterior cruciate ligament playing for the Lions against New South Wales Waratahs in June 2001. He spent nine months on the sidelines, but returned to pick up numerous honours, retiring after London Wasps won this year’s Guinness Premiership title

GOLF: Ernie Els

Mystery surrounds Ernie Els’s anterior cruciate ligament injury, suffered on a family holiday in July 2005 with rumours the South African damaged his left knee while water-skiing, on jet skis, or “tubing” from the back of a speed boat. He returned after six months but has struggled to find form

FOOTBALL: Paul Gascoigne

Paul Gascoigne’s anterior cruciate ligament injury put him out of football for 16 months. He damaged the knee while making a challenge on Gary Charles, of Nottingham Forest, while playing for Tottenham Hotspur in the 1991 FA Cup Final. Many believe that the midfield player was never the same again

CRICKET: Simon Jones

Simon Jones’s anterior cruciate ligament injury, suffered while sliding for a ball against Australia at the Gabba in November 2002, left him on the sidelines for nine months. Despite making an explosive comeback and taking 18 wickets in the 2005 Ashes, he has suffered lingering problems

FOOTBALL: Michael Owen

Perhaps the most sickening anterior cruciate ligament injury, the nation winced as Michael Owen’s knee was filmed collapsing in slow motion in the first minute of England’s 2-2 draw with Sweden in the 2006 World Cup. Owen spent ten months out and has rarely been off the treatment table