Australia's Olympic and world swimming champion Grant Hackett has pulled out of next year's Commonwealth Games to undergo immediate surgery.

Hackett told a news conference in Melbourne on Monday he had agreed to an operation this week to repair torn cartilage in his right shoulder.

Hackett, unrivalled as the world's best long-distance swimmer, said he is disappointed he would miss the Commonwealth Games in March for what is a relatively minor operation but said it is essential to his long-term plans.

"I want to ensure my longevity in the sport and I've still got a lot of things that I want to achieve in my career," he said.

"If I let it drag on it could get worse and worse and it could eventually become a major problem," Hackett said.

Hackett, 25, has been hampered by shoulder pain for years but the injury has deteriorated in the past few months because of the constant wear and tear from training.

His coach Denis Cotterell said that while could have competed at the Commonwealth Games in Melbourne he would have jeopardised his chances of competing at the 2007 world championships and 2008 Beijing [Images] Olympics [Images].

"His body is crying out for a rest," Cotterell told reporters.

"We need to be sensible about addressing it so his bigger goals with the worlds and the Olympics can still be met.

VIRTUAL CERTAINTY

Hackett was considered a virtual certainty to win the 1500 metres freestyle gold medal in Melbourne.

He is already the most successful endurance swimmer in history and his domination of the gruelling event has started to take on legendary proportions.

He is unbeaten over the distance since 1996 and his world record of 14 minutes 34.56 seconds is more than seven seconds faster than anyone else has ever swum.

Hackett won his first world title in 1998 and his fourth in a row at this year's world championships in Montreal, where he was named best male swimmer of the meet.

The Gold Coast law student has also won the past two Commonwealth titles and captured his first Olympic gold medal in Sydney five years ago then his second in Athens despite swimming the final with a partially collapsed lung.

He has his sights set on winning a third 1500m crown in Beijing as well as having a shot at the 10-kilometre open water event, which has been added to the programme for the first time.

"At the end of the day I've got to do what's best for my career," Hackett said.

"I'm fixing up a problem that is inhibiting my swimming and limiting what I can do.

"I figure I'm going to come back a better athlete. I'm going to have a stronger right shoulder and not have any pain there and be able to improve on my performances."