Uncapped Glasgow Warriors prop Moray Low has been forced out of the Scotland squad that travels to Argentina for the summer test matches next month.
Low had hoped play in Rosario or Buenos Aires but will instead recover at home.
Scotland team doctor James Robson said: "Moray will be subject to further assessment, but he will be in a compression boot for two weeks.
"He'll then have a period of four to six weeks of rehabilitation, which will rule him out of the tour."
The 23-year old Low's place has gone to 25-times capped Craig Smith, his opposite number at Edinburgh.
"We are still waiting to see if Simon Webster will recover from his hamstring injury to make the tour"
Smith has been promoted from the A-squad and had been due to take part in the Churchill Cup.
Scotland coach Frank Hadden has still to finalise his squad with more players set to be added.
But there will be no place for the injured Nikki Walker and Rory Lamont, with Glasgow's Max Evans, who has also been drafted in from the A squad.
Hadden said: "We have decided to promote Max Evans from the Scotland A squad.
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"Max has played well in the Magners League for Glasgow and is another to have benefited from involvement with both Scotland A and Scotland Sevens.
"We are still waiting to see if Simon Webster will recover from his hamstring injury to make the tour.
"He'll be subject to further monitoring and we'd hope to make a decision on Simon next week."
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