England back-rowers Courtney Lawes and Nathan Hughes are likely to miss the rest of the season with knee ligament injuries picked up in last weekend’s Six Nations defeat by France.
Northampton Saints’ Lawes, 29, and Wasps’ Hughes, 26, are expected to be out for about 14 and 12 weeks respectively after surgery.
Lawes has played every Six Nations game, while Hughes has appeared twice.
Exeter’s Don Armand has been called up for Saturday’s closer against Ireland.
The injuries could also hamper their availability for England’s summer tour of South Africa, which takes in three Tests around the country in June.
During the Six Nations, head coach Eddie Jones has looked to Lawes alongside former skipper Chris Robshaw to form the back row either side of emerging Exeter talent Sam Simmonds or the ball-carrying weapon Hughes.
Wasps could rue the loss of Fiji-born number eight Hughes in their bid to win the domestic Premiership, with Dai Young’s side currently seven points behind leaders Exeter.
Saints are currently 10th in the table – with Lawes figuring 15 times this season in between his international commitments.