Andrew Flintoff will undergo a scan on his injured hip tomorrow afternoon but England are sufficiently concerned about his fitness to have called up two players as cover.
Flintoff, 31, has a suspected muscle tear in his right hip but has not been ruled out of bowling today if required in England's bid to win the the third Test in Antigua.
In the meantime, fellow all-rounder Ravi Bopara and uncapped pace bowler Amjad Khan have both been summoned from England Lions' tour of New Zealand to bolster the Test party here.
"They are coming because Fred has hurt himself and will be here as soon as possible," said assistant coach Andy Flower.
"People will have seen yesterday that he cannot move properly because of some problem in his hip.
"There is a limit to how much we know about the injury at this stage but he is going to give bowling a go.
"He is struggling to get it through at full pace but if we need him he will bowl."
With back-to-back Tests in Barbados and Trinidad starting next Thursday, however, Flintoff's latest injury setback is a blow to England's hopes of overturning their current series deficit.
Flintoff remains crucial to balancing the side and the very fact that the England management team have called in two reinforcements highlights the complication of accounting for his absence.
He only began the campaign after passing a fitness test on a left side strain.
"He knows his body very well and he will feel whether he can do the job," Flower added.
"Even at three-quarter pace he can still do a job for us. But it's finding a balance between winning the Test and not doing any lasting damage.
"We don't know what the injury is at this stage and an MRI scan will give us more information.
"The medical guys think there might be a little tear there, they're not sure, but it is a muscle problem in his hip."
Flintoff only returned from a long-term ankle injury for the second Test of four against South Africa last summer.
"Fred works really hard at his fitness but I think through workload and wear and tear over the years he keeps picking up these little injuries," said Flower.
"He is a strong bloke both physically and mentally and he will get himself right hopefully."
Bopara and Denmark-born Khan are expected to join up with the 16-man touring party in Barbados on Saturday.