Exeter forward Jacques Vermeulen is set for an extended period on the sidelines after undergoing shoulder surgery.
"It was a relatively big operation," Exeter boss Rob Baxter said.
"He was holding on until we got to the end of the season, so he's going to be out for an extended period."
With Jonny Hill, Jonny Gray and Sam Skinner all away on international duty, Vermeulen's absence will put pressure on Exeter's second-row, with the former Sharks player able to play at flanker or lock.
"We may look at Don Armand in a slightly different role, he's played a lot of second-row before and we may look at him in a role around there," Baxter said.
"We've got a couple of young back fives also in the academy who are starting to show some promise so it creates an opportunity for them."
Meanwhile, Exeter have also received a boost with England hooker Luke Cowan-Dickie returning to training ahead of Friday's Premiership opener against Harlequins.
The forward had undergone minor knee surgery after the Premiership final win over Wasps last month.