England prop Mako Vunipola's knee injury puts his Six Nations in doubt
England prop Mako Vunipola's participation in the RBS Six Nations Championship is in doubt.
Vunipola suffered suspected ligament damage in his left knee after being forced off in Saracens' European Champions Cup win at Sale last weekend.
The 25-year-old is expected to see a specialist in the next fortnight when the swelling on the knee subsides.
But Press Association Sport understands that his club Saracens have put a time frame on Vunipola's potential absence as between four to 12 weeks.
If a scan highlights minimal damage, then Vunipola should be fit for England's Six Nations opener against France at Twickenham on February 4.
But a more serious injury could rule Vunipola out of the entire tournament and prevent him from being part of England's title defence.
That would be a huge blow for England coach Eddie Jones as the 39-times capped Vunipola has played a major part in the team's success during 2016.
The New Zealand-born prop featured in every game of England's Grand Slam-winning campaign, as well as the 3-0 summer series win in Australia and the four autumn Test victories.
Vunipola has certainly been ruled out of Saracens' festive programme, which sees the Aviva Premiership leaders host Newcastle today before travelling to Leicester on New Year's Day.
Saracens then host Exeter in the Premiership on January 7 before concluding their Champions Cup group fixtures against Scarlets and Toulon.
Coach Mark McCall said Vunipola's absence would be a loss for the English and European champions ahead of a crucial run of games.
"Mako has got a bit of soreness in his knee which will be assessed," McCall said after the Sale victory.
"Anybody would miss Mako Vunipola but we don't know how long he will be out for yet."