Wales lock Ian Evans may require reconstructive shoulder surgery and looks certain to miss the remainder of the season.
The 22-year-old Ospreys forward suffered a partial dislocation during the match against Cardiff Blues on December 23 and his club are fearing the worst as they await the results of a scan.
If their fears are confirmed, Evans will miss the RBS Six Nations Championship and will be a doubt for October's Rugby World Cup.
"Ian looks likely to be out until June," said the region's physiotherapist Brian Downey.
"It isn't great news for him or for the Ospreys because we are going well in the Heineken Cup and Ian is an important part of our team.
"But there should still be an opportunity for him to prove his fitness for the World Cup.
"It looks like the same problem that saw our hooker Richard Hibbard undergo surgery earlier in the season. It will be a six-month lay-off for Richard and probably the same for Ian."
Evans is now expected to miss the Ospreys' Heineken Cup challenge, the Six Nations and Wales' end-of-season tour to Australia.
However, should he make a speedy recovery he could return for the World Cup warm-up matches against England, Argentina and France in August, bringing him back into contention for the World Cup.
Evans has missed only one of the last six internationals and is seen as an important member of the Welsh pack.