Richie Gray has been ruled out of Scotland's Six Nations clash with Italy at Murrayfield on Saturday by a hamstring strain.
Lock Gray picked up the injury in last weekend's record-equalling defeat by England at Twickenham and failed a fitness test on Friday.
He is replaced by Edinburgh second-row Grant Gilchrist, who comes straight into the starting side for his first appearance in this year's Six Nations.
Tim Swinson, who has been Scotland's replacement lock in all four matches to date, remains on the bench.
"We felt the way they both play, Tim would be better to start on the bench, and Grant - with the things he offers around the pitch - would be better suited to start," said Scotland resource coach Nathan Hines.
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Gilchrist, whose Test career has been disrupted by a series of injuries, won the last of his 15 caps as a replacement in Scotland's final autumn Test against Georgia.
Saturday will be only the 26-year-old's second Six Nations match - the first since his debut against France in Paris four years ago.
