England No. 8 Billy Vunipola will miss the entire 2018 Six Nations campaign after Saracens confirmed he suffered a fractured forearm last weekend.
Vunipola has had a very difficult time with injury, having missed the British & Irish Lions tour of New Zealand last summer after injuring his shoulder.
In September he was then ruled out for almost four months after undergoing knee surgery to repair the meniscus on his right knee and his latest injury looks likely to rule him out until April.
"Having now seen a specialist, we can now advise that Billy's recovery will take approximately 12 weeks," Saracens said in a statement. "We will continue to monitor Billy's injury and of course provide the necessary support framework to get him back and fully fit."
Jack Clifford, Matt Mullan, Nathan Hughes, Beno Obano and Ellis Genge also join Vunipola on the list of absentees from Eddie Jones' squad announcement, which sees eight uncapped players named.