Mako Vunipola a doubt for Six Nations with knee injury

England prop Mako Vunipola has emerged as a doubt for next year's Six Nations after picking up a knee injury.

The 25-year-old was forced off during Saracens' European Champions Cup win over Sale Sharks last weekend with suspected ligament damage in his left knee.

Vunipola will see a specialist in the next fortnight to determine the full extent of the problem, but reports suggest that he will be sidelined for up to 12 weeks.

Should the scan reveal minimal damage to the ligament then Vunipola could be fit in time for when England begin the defence of their crown against France at Twickenham on February 4. However, if the injury is serious then Vunipola is expected to miss the entire tournament.

Mako's brother Billy Vunipola has already been ruled out of the Six Nations with a knee ligament injury of his own.