England centre Manu Tuilagi has suffered a setback in his recovery from a groin injury.
Leicester Tigers boss Richard Cockerill suggested earlier this month that Tuilagi would return before Christmas, but he could now be out until the middle of January.
The 23-year-old suffered the injury in a game against Ulster in October, and he was ruled out of England's Autumn Internationals.
Stuart Lancaster was confident of having Tuilagi back for the beginning of the Six Nations, but the England head coach could be forced to look at other options if the Tigers centre continues to struggle with the problem.
England start their Six Nations campaign against Wales in Cardiff on February 6.