Wayne Rooney will fly to Germany with the rest of England's squad on Monday, despite the date for a scan on his injured foot being brought forward.
England manager Sven-Goran Eriksson wants to analyse Rooney's fitness ahead of the scan in Manchester on 7 June.
A Football Association statement read: "Wayne will be accompanied by England doctor Leif Sward who will then analyse the scan with Manchester United."
Eriksson has until 9 June to decide whether to name Rooney in his squad.
Leading orthopaedic surgeon Mark Bowditch told BBC Sport Rooney's progress will depend on the location of damage to his injured foot bone.
"If the fracture occurs to the lower part of the bone, where it is narrower, it will take longer to heal," he said.
"Usually eight to 10 weeks is the recovery time for this sort of injury."
England manager Sven-Goran Eriksson has brought forward Rooney's next scan to 7 June - a week earlier than originally planned.
The move would give Eriksson the option of calling up reserve strikers Jermain Defoe and Andy Johnson should the results of the Rooney's scan confirm the striker will not be able to participate at any stage during the World Cup.
Manchester United doctors have booked a computed tomography (CT) scan to determine the extent of damage to Rooney's fourth metatarsal.
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"The CT scan will give doctors a 3D picture of the bone and the level of calcium, which determines how well the bone is progressing," said Bowditch, a consultant orthopaedic surgeon and advisor to Ipswich Town and Colchester United.
"The metatarsal has two ends and a middle. The ends tend to heal a lot quicker, but it gets more troublesome if the fracture is towards the middle."
However James Bliss, a consultant orthopaedic surgeon at Guys and St Thomas' hospital in London, warned a positive scan result could still put Rooney at risk.
"There's only a finite speed of which a bone can heal," he said.
"Being an elite athlete Rooney would probably heal quicker than some, but only time will tell.
"The fear is if he comes back early he runs the risk of breaking down again, which is probably what is concerning (Manchester United manager) Alex Ferguson as any setback will mean a long-term problem."