Glasgow Warriors prop Moray Low has been forced out of Scotland's squad for the two-Test trip to Argentina next month.
The news comes as a huge blow for Low after he, along with Glasgow team-mates Max Evans and brother Thom were only named in the senior squad for the first time six days ago.
The uncapped 23-year-old has been told it will take at least six weeks to recover from the ankle injury he sustained in Glasgow's Magners League win against Munster on Saturday.
Edinburgh's 25-cap prop Craig Smith has been promoted from the Scotland A squad to replace Low.
Scotland team doctor James Robson said: "Moray will be subject to further assessment but on reviewing the X-ray he will be in a compression boot for two weeks then undergo a period of rehabilitation of between four to six weeks, which will rule him out of the tour."