Gloucester fly-half Danny Cipriani has been sidelined for up to six weeks after suffering a "small tear" to a chest muscle.
England international Cipriani sustained the injury during his club's 29-17 Heineken Champions Cup defeat to Exeter Chiefs on Friday.
"He's got a small tear in the muscle in his pectoral, so he's going to be out for anything from four to six weeks," Gloucester head coach Johan Ackermann told Gloucester Live.
"Obviously he's been part of every game this season and played a lot of those games 80 minutes, so it is a big challenge now for us to get through this block without him."
Gloucester also lost Italy international Jake Polledri to injury on December 8, during the first match of their double header with Exeter.
According to Gloucester Live, the flanker will undergo an ankle operation and is set to miss 10 to 12 weeks.
"Jake is out unfortunately. It's a similar operation that Ruan (Ackermann) had four weeks ago," added Ackermann.