Initial press reports suggested that the Frenchman could be out for up to a month, but the results of a scan were less pessimistic.
"Laurent jarred his right knee at Birmingham," said a club spokesman.
"A scan revealed some internal bruising, and he is under treatment for the injury."
Should Robert miss out against the Foxes there will be plenty of candidates hoping to take advantage of the situation to stake a first-team claim.
Craig Bellamy, Shola Ameobi and Michael Bridges will all be hoping to start up front alongside Alan Shearer, leaving Kieron Dyer available to drop back into midfield, although that could be at the expense of either Jermaine Jenas or Darren Ambrose.
Hugo Viana will no doubt be waiting anxiously to see whether or not this is the opportunity he has been hoping for, although he has never really looked comfortable in wide positions.
The most likely possibility is a return to the first team for a fit again Lee Bowyer, who performed well on the left of midfield in the 1-0 win over Southampton earlier in the season.