(CNN) -- England will make a late decision on Andrew Flintoff's fitness on the morning of the fourth Ashes Test against Australia in Leeds, with both teams troubled by injuries.
Andrew Flintoff is still struggling with his knee injury ahead of the pivotal fourth Test at Headingley.
The presence of all-rounder Flintoff at Headingley will be a key factor for both sides, but England will give him every chance to shake off the knee problems that were a major factor in his decision to retire from the five-day game at the end of this series.
The 31-year-old, who has needed painkilling injections to play in the previous two Tests, managed 35 minutes of bowling practice in the Headingley nets on Thursday morning.
"We need to see how he reacts to the work he did today -- and we probably won't know that for sure until the morning," captain Andrew Strauss told the UK Press Association.
"It's no different this time. That's been the situation pretty much the whole way through the series. If he's fit enough to do his job in the side then he'll play. If not, he won't."
With England protecting a 1-0 series lead with two matches to play, Strauss is wary of the ramifications of fielding an unfit Flintoff.
"We are close to the finishing line and although we are all desperate for him to play, we need to be realistic enough to realize if he's not fit he shouldn't play," the opening batsman said.
"If he is fit then we are desperate for him to play. Judging whether he is fit or not comes down to a multitude of factors."
If Flintoff cannot take the field, England have called up Jonathan Trott in the possibility of playing a six-batsman line-up, while left-arm seamer Ryan Sidebottom was also recalled and would vie for a place with Steve Harmison if five bowlers are again included.
Ricky Ponting, who is seeking to avoid becoming the second Australia captain to lose two Ashes series in England, hopes to have key fast bowler Brett Lee back in his line-up.
The 32-year-old has been sorely missed, having sat out the first three matches with a side injury, but is badly lacking in match practice despite his return to fitness.
Wicketkeeper Brad Haddin missed the previous draw at Edgbaston due to a broken finger, while vice-captain Michael Clarke is also an injury doubt with a stomach strain.
Seamer Stuart Clark is hoping for a recall, with spinner Nathan Hauritz possibly the man to make way.
Ponting has confirmed that he was abused by a spectator at Edgbaston on Sunday following his dismissal in Australia's second innings.
"There were some words exchanged. The spectator was actually leaning over the front of the grandstand and gave me a bit of a gob-full when I got out," he told PA.
"As it turned out, he was later thrown out of the ground -- so it would appear he was probably in the wrong."
The incident has so upset the England and Wales Cricket Board that chairman Giles Clarke has urged fans to behave with more respect.
However, Ponting said he was not worried about the matter.
"It's part and parcel of what we do. It happens everywhere around the world, and it's no bigger deal here in this series than what it has been in others I've played."