England are facing an anxious wait to determine whether they face another dilemma over the balance of their side after all-rounder Andrew Flintoff emerged as a doubt for the second Ashes Test.

The 31-year-old Lancastrian reported soreness and stiffness in his right knee during the drawn opening Test in Cardiff. The knee was operated on earlier this year following an injury sustained during Flintoff's stint playing in the Indian Premier League.

Flintoff was taken for a precautionary scan yesterday and will be further assessed over the next 48 hours before England name their line-up for Thursday's second Test. Durham fast bowler Steve Harmison has been recalled to a 14-man squad as cover.

But if Flintoff fails to recover in time for the next encounter against Australia, at Lord's, it will present major problems for England as Flintoff provides balance by being one of five specialist bowlers and batting at No 7. Stuart Broad could be moved up one place in the order to take Flintoff's position, but after his disappointing display with the ball in Cardiff, England may be reluctant to saddle a young player with even greater responsibility.

Their other option is to include Ian Bell as one of six specialist batsmen, but that could dilute their bowling options and captain Andrew Strauss is known to favour five specialist bowlers in his line-up.

Publicly, England are playing down the seriousness of Flintoff's problem, but with just three days between Tests they must be privately concerned about his readiness for Lord's.

"I don't think it's a flare-up, it's just a reaction to one of his old knee injuries, but I don't think it's bad from what we can make out," revealed national selector Geoff Miller yesterday. "It's not disastrous but we just have to be very wary of it and monitor it and we've produced a selection to cover that." The selectors consider Harmison as a like-for-like replacement for Flintoff because of the pace and bounce he provides, but he presents a problem with the batting line-up.

"In the event of Andrew being unfit, we see Stephen as a like-for-like replacement in terms of the type of bowler he is and his ability to unsettle the opposition batsmen with pace and bounce," confirmed Miller.

"But we will need to consider all our options carefully when we come to determine the make-up of our bowling attack at Lord's and the final decision will depend on our assessment of the pitch and the likely overhead conditions."