Gloucester flanker Lewis Ludlow will be out for two months after scans revealed he fractured his wrist.
The 24-year-old is available to return from a four-week ban this weekend but will now not feature until 2019.
"He picked up a wrist injury in the Wasps game but never really took note of it," coach Johan Ackermann said.
"It kept aching and when we trained last week he got a bang on it and it got worse. We scanned it and there was a fracture."
Meanwhile, hooker Franco Marais (shoulder) and utility back Tom Marshall (hamstring) will both be out for about three months after requiring operations on injuries picked up in the European Champions Cup defeat by Munster last month.
Number eight Ben Morgan is also receiving treatment on a shoulder injury he picked up on England duty.
However, club captain Willi Heinz is set to make his comeback from a calf injury in the Premiership Cup game against Northampton Saints on Friday night.
The 31-year-old scrum-half has not featured for the Cherry and Whites this season.
"He has put a lot of effort in so let's hope and pray this is the return we are all hoping for," Ackermann told BBC Radio Gloucester.
"As the captain he is still a leader but for this coming weekend we will manage him and, unless we can't foresee it, he won't play the full 80 minutes.
"The chance is somebody else will be captain this weekend but it will be good to have him back."
Gloucester host Northampton in the Premiership Rugby Cup on Friday, before resuming their Premiership campaign with a home fixture against Leicester on Friday, 16 November.