England fly-half Owen Farrell is a serious doubt for the opening weekend of the Six Nations with a knee injury.
The 23-year-old picked up the injury during Saracens' defeat to Clermont Auvergne in the European Rugby Champions Cup, and he was seen leaving the stadium on crutches after the match.
Saracens director of Rugby, Mark McCall, told reporters: "It's a new injury and we don't know the extent of it just yet. It's complicated with knee injuries, sometimes you can do that [walk off] and it's more serious, but we'll get him looked after and we'll know in the next few days."
England open their campaign against Wales in Cardiff on February 6.
