England fly-half Toby Flood is a doubt for the Six Nations opener with Scotland on February 4.
The 26-year-old has suffered a knee injury which could keep him out for up to six weeks, ruling him out of the Scotland clash and making him a doubt for the game against Italy a week later.
Flood suffered the injury while on club duty with Leicester Tigers.
Richard Cockerill, Leicester's director of rugby, said: "Toby has had a bang on the knee and it's being treated. We'll just have to wait and see how it progresses."