Ryan Jones has given Wales an injury scare 10 days before their autumn Test series opener against Argentina.
The Ospreys back-row forward is on his way home from Wales' training camp in Poland to undergo scans on what the Welsh Rugby Union said was "an irritable shoulder".
Wales have already lost two of last season's Six Nations Grand Slam stars - prop Adam Jones and flanker Dan Lydiate - for the entire series that features appointments with Argentina, Samoa, New Zealand and Australia
The vastly-experienced Jones, who has been in impressive form for the Ospreys this season, is the favourite to replace Lydiate.
Wales interim head coach Rob Howley is due to announce his team for the Pumas clash tomorrow week.
Jones, 31, headed to Spala in Poland with the Wales squad three days ago, and the WRU said he had been managing a shoulder problem prior to that.
A WRU statement read: "The decision to send Jones home at this time is based on a preference for the facilities available in Wales to accommodate the necessary investigations and give the player the most optimal management plan for his injury.
"Jones remains a full member of the squad and further details of his problem and any repercussions for selection, if at all, will become apparent once the proper investigations have been undertaken."
"The decision to send Jones home at this time is based on a preference for the facilities available in Wales" - WRU statement
Adam Jones was ruled out of the autumn series last week due to a knee problem that could require more than two months' rehabilitation.
Lydiate, meanwhile, suffered a serious ankle injury playing for Newport Gwent Dragons earlier this season.
In addition to missing the autumn schedule, it is unlikely he will play any part in Wales' Six Nations title defence, although he is expected to regain full fitness ahead of next summer's British and Irish Lions tour to Australia.
Lydiate was last season's Six Nations player of the tournament, although Wales have a ready-made replacement in Ryan Jones, who is a former Test skipper and has won 67 caps.
