Saracens's Chris Jack will be out of action until after Christmas following knee ligament damage, the club said Wednesday.

The former New Zealand forward was injured in the second half of Saracens' European Challenge Cup victory over Viadana on Saturday and faces up to eight weeks on the sidelines.

"The news about Chris Jack is very disappointing, but it's just something we have to deal with," said director of rugby Eddie Jones.

"It's good to have David Seymour back and available. He's returned two weeks ahead of schedule from pretty much the same injury that Chris has suffered," the former Australia coach added.

But Saracens will have the consolation of knowing South Africa back-row forward Wikus Van Heerden will join up with the club on Tuesday

Van Heerden, one of three new arrivals, will head to England after playing for the Blue Bulls in Saturday's Currie Cup final against the Sharks.

Saracens' other new South African recruit, the centre Brad Barritt, is in the Sharks squad for the Durban showdown.

Jones, who worked as a consultant to South Africa's World Cup-winning side last year, said: "It should be a good game in Durban, but my money in on the Bulls to win it by eight.

"They have adapted really well to the ELVs (experimental law variations) and with Van Heerden in the side, Victor Matfield controlling the lineout and Morne Steyn at fly-half, I think they will have the edge."

Australian centre Ben Jacobs, Saracens's other late arrival, got into England on Tuesday from New South Wales and could make his debut for the Premiership club in their Anglo-Welsh Cup tie against Bristol on November 1.

AFP