Gloucester scrum-half Joe Simpson will be out for at least two months with an ankle injury.
The 31-year-old once-capped England international joined the Cherry and Whites from Wasps in 2019.
He has played in all 10 of Gloucester's Premiership matches so far this season.
"Unfortunately for Joe it's more serious than we expected so he's going to be out for eight to 12 weeks," Gloucester head coach Johan Ackermann told BBC Radio Gloucestershire.
Ackermann's side travel to London Irish in the league on Saturday [15:00 GMT].