Flintoff now has only one more match before his retirement from Tests
England's Andrew Flintoff has been ruled out of the fourth Ashes Test at Headingley because of his knee injury.
The 31-year-old wore strapping on his troublesome knee during net practice on Thursday, but was only able to bowl for 35 minutes at three quarter pace.
England left it until 0920 BST to make the decision on Flintoff, who was replaced by fast bowler Steve Harmison.
Flintoff now faces a race to be fit for the final Test at The Oval on 20 August, his last before he retires.
The England and Wales Cricket Board revealed more details about Flintoff's condition in a statement to the media on Friday afternoon.
It said: "In order to give Andrew a chance of playing in the second and third Test matches, he received a series of artificial synovial fluid injections into the knee joint and cortisone injections into some of the bursa on the outside of the knee joint to help settle the inflammation.
"There have been some media reports of repeated cortisone injections into the knee to mask the injury, but these reports are inaccurate.
"Andrew has shown great determination and selflessness making a conscious decision to push through discomfort in order to help the England team reclaim the Ashes.
"This is in the knowledge that a further operation is a possibility.
"Andrew is still very keen to play in the fifth Test at The Oval and a decision on this will be made in due course. He will not be exposed to undue risk or masking injections and any decision regarding his participation in the fifth Test will be made in conjunction with the ECB, his surgeon and the Lancashire medical team."
Flintoff, the star performer in England's epic Ashes triumph of 2005, announced before the Lord's Test that he was going to quit Test cricket after this series because of his ongoing injury problems.
But the all-rounder has since had an influential role in the current Ashes battle, taking 5-92 on the final day to inspire victory at Lord's which gave England a 1-0 lead, and top-scoring for the team with 74 in the draw at Edgbaston.
The Lancastrian denied suggestions that his involvement in the Indian Premier League Twenty20 event earlier this year caused his Test career to end prematurely.
"Going to the IPL wasn't the cause of it," he told BBC Radio. "I've got a degenerative problem with my knee and if I'd been playing that week for Chennai in Durban or for Lancashire in a four-day game against Sussex, the same thing would have happened.
"I can't blame going to the IPL for my knee, it's something which is there, and something which I'm dealing with.
"The flip-side of that is the problem was addressed then - I got it operated on - which enabled me to start the Ashes. I know I'm struggling again now but I was better off finding out then than two weeks before this series."
Looking ahead, Flintoff is confident that Test cricket will still be regarded as the pinnacle of the sport by the game's leading players.
"I don't think the lure of Twenty20 cricket will affect people's decisions in Test cricket," he said.
"We've seen how special it is in the Ashes and there's a lot of series which are great to play in - England go to South Africa this winter - and as a player, all these opportunities - to play in the IPL and that - have come about by playing Test cricket and making your name in that.
"Tests have a massive part to play in international cricket. Maybe towards the end of people's careers they might choose to do what I've done but I reckon for the bulk of people's careers, they'll want to play Test cricket."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.