Leicester fear Levi Porter may have suffered cruciate knee ligament damage in Wednesday's Carling Cup defeat to Chelsea.
The 20-year-old midfielder was stretchered off in the closing stages of the Foxes' 4-3 defeat at Stamford Bridge and Leicester are now awaiting the results of a scan before the full extent of the injury is known.
Caretaker manager Frank Burrows has revealed that the initial diagnosis does not look promising.
"We do not know the full extent of Levi's injury at the moment but it is not looking good," said Burrows, "I have heard the word cruciate which is obviously not good.
"Our medical team will have the area scanned and we should be in a better position to confirm the injury soon."
Meanwhile, Burrows admits it is difficult to accept Leicester's defeat after watching his side match Chelsea for the majority of the 90 minutes.
Chelsea netted twice in the final three minutes, through Andrei Shevchenko and Frank Lampard, to earn a thrilling win but Burrows remains proud.
"To have come so close is a bitter pill to swallow but we have to do that," Burrows added.
"Chelsea have not been beaten at Stamford Bridge for 60-odd games and there have been far bigger and better football clubs than Leicester go away with their tails between their legs.
"They were the better side. The quality of passing was better than ours and they had more possession but our hearts were as big as theirs.
"Where we matched them and maybe shaded them was our heart and fighting spirit."