World Cup 2010 - King's World Cup may be over
It was hoped that King, who was substituted at half-time in the opening draw with the United States, would be absent for only the second Group C game with Algeria on Friday.
However the latest prognosis for the injury-prone Tottenham centre-half is that "he has damaged an adductor muscle" - according to the morning's newspapers - which carries a three-week recovery period.
A spokesman for the FA refused to confirm the reports but said King's situation would be clarified later on Monday.
"There is nothing to say but there will be an injury update later today," he said.
Should he face three weeks out, King could return for a possible quarter-final tie, but Fabio Capello may be unwilling to risk him in high-profile end-of-tournament matches.
Slovenia top the group after a 1-0 win over the North Africans on Sunday.
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