Wales and Ospreys flanker Dan Lydiate is set to miss a few months due to knee ligament damage, meaning he may miss the start of the Six Nations.
Lydiate suffered the injury during Wales 27-13 win over South Africa last weekend in Cardiff.
As a result the Lions back-row will miss key fixtures in the PRO12 and Champions Cup for the Ospreys, and possibly the Six Nations opener for Wales up against Italy in Rome.
"It's not great, there's definitely some ligament damage," Ospreys head coach Steve Tandy told BBC Wales Sport.
"It will be a bit more than a couple of months.
"The worst thing is for Dan, it's off the back of some bad luck with injuries and he was starting to come back into a bit of form.
"Ultimately I'm just disappointed for the boy, whoever he was playing for, Wales or Ospreys. I'm just pretty gutted for Lyds."