Cornish Pirates lock Laurie McGlone is set to be out until at least March after injuring his shoulder.
The 36-year-old forward was hurt in the 33-26 loss at Yorkshire Carnegie.
New Zealand-born McGlone has been with the Pirates since 2009 and has scored nine tries in 141 games.
"He's seeing a specialist to see the extent of it, but he's going to be out for a few weeks. We don't know the extent of it just yet," Pirates coach Gavin Cattle told BBC Radio Cornwall.
"Laurie's a massive man, not just on the pitch, but off the pitch for us. He's massive in stature and a massive personality around the club as well.
"It is going to be a big blow when you lose somebody like that, but there's an opportunity there now for some of the boys to step into his shoes, which are big shows to fill."