ENGLAND have admitted they are concerned about Andrew Flintoff's long-term future as an international all-rounder as he battles to recover from a recurrence of knee problems to prove his fitness for this week's second Ashes Test.

The 31-year-old all-rounder was given a further cortisone injection in his right knee after reporting discomfort during England's long spell in the field in the dramatic drawn opening Test in Cardiff but England are optimistic he will be fit enough to play at Lord's tomorrow.

But, after suffering problems with his knee in his first international match since returning from surgery, England have admitted to concerns about Flintoff's ability to withstand the rigours of Test cricket on a long-term basis.

Flintoff batted during yesterday's practice session at Lord's but will not bowl until tomorrow to give the injection time to settle and England will delay their decision on their final line-up until after tomorrow's practice.

"He saw the surgeon that operated on his knee recently and his surgeon was quite optimistic with him playing in this game,’’ explained England coach Andy Flower.

"The suggestion is that he should be okay but we can only make that decision today. I think with Fred and his injury record we're always concerned, to be honest.

"His body's in that sort of state at this time of his career when he seems vulnerable a lot of the time and we can't get away from that but he's a hell of a player and we want him in our side when he's fit.’’ Close friend Steve Harmison, who missed yesterday's practice because he bowled extensively for Durham in the drawn LV County Championship match against Yorkshire at Headingley, has been drafted into the squad as cover.

But if Flintoff is ruled out, it provides England with a delicate balancing act for Lord's, where they have not beaten Australia since 1934.