Jones has taken 59 wickets in 18 Test matches for England
Worcestershire and England fast bowler Simon Jones has had keyhole surgery on his left knee but hopes to be fit within six weeks.
It is a massive blow to the Ashes hopes of the 30-year-old, who appeared to be on his way back to full fitness after an operation in September 2008.
Jones's management company, Wasserman Media Group, said surgeon Andrew Williams had removed scar tissue.
They added that Jones hoped to "attain match fitness within six weeks".
A statement said: "Contrary to reports this was a planned procedure following diagnosis by Worcestershire medical staff during the county's pre-season camp in South Africa.
"Simon will immediately return to training with Worcestershire with a view to attaining match fitness within six weeks."
Speaking on Tuesday, before he knew he would have to go under the knife once more, the injury-prone Welshman said: "I want to come back when I am right, rather than rushing things. It's been a tough winter, but I have worked hard on my fitness."
The former Glamorgan man has not played for England since the fourth Test of the 2005 Ashes series and said any hopes he has of returning to international cricket hinge on him proving his fitness at domestic level.
"Any English cricketer wants to play for their country, but I am focusing on my cricket for Worcestershire," said Jones.
"If I can play well for my county and get wickets I know I will be pushing for a place.
"I do believe in myself but I am not looking too far ahead. I'm just going to get as fit as I can."
Jones had taken part in Worcestershire's pre-season tour of South Africa, but Rhodes admitted to BBC Hereford & Worcester earlier this month that the Welshman was always facing an uphill battle to be fit for the start of the 2009 campaign.
"He was a bit slower than we had planned and didn't get out there in a match situation," said Rhodes.
Worcestershire began their County Championship campaign against Hampshire at the Rose Bowl on Wednesday.
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