Billy Vunipola will miss the rest of the season with a knee injury that has jeopardized his chances of winning the World Cup.

Saracens No8 was carried off the Stade Marcel Deflandre field on a stretcher in Sunday’s 24-10 loss in the Champions Cup quarter-final at La Rochelle.

Vunipola underwent some explorations yesterday that have led Saracens to rule him out for the remainder of the current campaign.

Barnet club bosses have not put a clear timetable on Vunipola’s recovery, but the 30-year-old will now face an uphill battle to be ready for the autumn World Cup in France.

“Billy is an important player on and off the court for us in terms of who he is as a senior player,” Saracens assistant coach Kevin Sorrell said. “His influence will be missed. During the last four or five weeks we had been very pleased with what we had seen of Billy.

“He hurts us a lot with and without the ball. Anyone who has had a long-term injury has two sides. There’s the physical side and there’s the mental side as well and the support you need around that. Everyone will be looking out for Billy.”

Vunipola has achieved good form with Saracens this season, but was omitted from new England boss Steve Borthwick’s Six Nations squad.

The powerful ball carrier was keen to use the business end of this campaign to make his case for an England return, as an added bonus amid helping Saracens push for even more honours. Now both joint goals are gone, and Sarries must manage without another striker in the back line for the end of their Premiership campaign.

Theo McFarland was already long absent after knee ligament surgery, while Andy Christie suffered a broken arm in the Champions League last 16 win over Ospreys that also ended his season prematurely. .

The return to fitness of second row Callum Hunter-Hill offsets the growing concerns of the back row, with Nick Isiekwe and Maro Itoje both options to appear on the back row and also blocked.