England have suffered a serious injury blow ahead of the Six Nations after it was confirmed that Billy Vunipola has fractured his forearm.
Vunipola was withdrawn at half-time of Saracens' 15-15 draw at Ospreys Saturday and a subsequent x-ray has revealed the extent of the fracture.
The No. 8 will see a specialist this week in order to establish a timeframe for his recovery, but it is now extremely doubtful that he will be involved when England's Six Nations defence kicks off against Italy on Feb. 4.
England boss Eddie Jones was already planning for the first three weeks of the championship without Wasps No. 8 Nathan Hughes, and will hope Vunipola is able to make a speedy recovery from his latest setback.
Vunipola, 25, was making only his second appearance following a 15-week layoff after knee surgery. If he is required to undergo an operation on his forearm, it will be his fourth in a little over a year.
"Billy is due to see a specialist later this week, when a timeframe for recovery may be defined," a Saracens spokesman said in a statement.
"But until that time Saracens will make no further comment. Saracens will issue a further statement once Billy has seen a specialist."