Scotland forward Jim Hamilton has returned home from the nation's tour of South Africa to be with his expectant wife.
As a result, Rob Harley, who already has three caps, has been called into the squad for the remainder of the tour.
"It's amazing to be called up to the Scotland tour. I came in last week for pre-season training with Glasgow and wasn't expecting to get the call, so it's a bit of a shock but very exciting," Harley told BBC Sport.
"I've never been out to South Africa before, so it'll be good to go over there and hopefully I'll be able to make the squad for the game on Saturday. The game against Italy in the Six Nations was my first start for Scotland, so I know a little about them.
"But I'm sure it'll be a different game over in South Africa with different conditions. I'm excited about the challenge and I hope I get the chance to show what I can do."
Scotland were defeated 30-17 by South Africa on Saturday.
