A hamstring tear has forced England captain Michael Vaughan out of Friday's one-day international against Australia in Brisbane and threatens to prematurely end his tour.
England officials are unsure how long the injury will sideline the 32-year-old, but have called up Lancashire batsman Mal Loye as a precaution.
Vaughan has been allowed to remain with the squad but will undergo a reassessment in the next 48 hours after scans revealed he had suffered a grade one tear.
Vaughan injured himself while fielding in England's three-wicket win over New Zealand in Hobart on Tuesday and although he was able to bat, the Yorkshire opener had to call for the assistance of a runner.
England are yet to decide who will skipper the side in Vaughan's absence although the choice is certain to be either Andrew Flintoff or Andrew Strauss.
Flintoff captained England in their 5-0 Ashes Test loss to Australia but coach Duncan Fletcher later said the burden of leadership had affected his game.
Flintoff has been in great form since Vaughan resumed the leadership and was named man of the match after scoring an unbeaten 72 against New Zealand on Tuesday as England chalked up their first win of an otherwise disastrous tour.
Vaughan, 32, has only just returned to the England fold after two operations on his right knee.
He missed more than a year of international cricket including the Ashes Tests but was recalled for the triangular one-day series after passing a fitness test.
Were Vaughan to be ruled out of the rest of the series, it would be another huge blow to England who have already lost their best batsman Kevin Pietersen, who broke a rib batting against Australia last week.
Loye, 34, is uncapped at international level but was named this week in England's preliminary 30-man squad for the World Cup.
He is the second new player in a week to join England's one-day squad in Australia after Ravi Bopara replaced Pietersen.
