Wales flank Ryan Jones has been ruled out of the clash with Argentina this weekend due to a shoulder injury.
The experienced loose forward was sent home early from the team's training camp in Spala, Poland, last week for scans on the shoulder which had been troubling him over recent weeks.
On reviewing his results, Wales medical staff have decided Jones needs a further period of rest in order to fully recover from the problem, thus ruling him out of contention for the Pumas game, but they expect him to be back in time face Samoa on Friday November 16, if required.
Wales assistant coach Robin McBryde said: "We took the decision out in Poland, we were aware Ryan had a niggle with his shoulder coming out to Poland so we thought it would be wise to get in there early and investigate if it was anything serious.
"Happily enough that isn't the case, but it is a case of doing quite a bit of rehab work for the remainder of this week in order for him to be fit for next week's match against Samoa, which is positive news."
Jones's injury is the latest setback for Wales ahead of a series featuring Tests against world champions New Zealand and Australia.
Newport Gwent Dragons flank Dan Lydiate is a long-term absentee after breaking his ankle on regional duty while tighthead prop Adam Jones, the anchorman of Wales's scrum, will also miss all four of the upcoming Tests because of a knee injury.
Interim head coach Rob Howley, in charge after Wales boss Warren Gatland's secondment to the British and Irish Lions for next year's tour of Australia, is due to name his matchday 22 to face Argentina on Tuesday.