Scotland captain Blair was handed a belated Lions call-up by coach Ian McGeechan following a serious ankle injury to Munster and Ireland scrum-half Tomas O'Leary.
The Scotsman should prove a more than adequate replacement judging by the string of eye-catching performances he has put in for both club Edinburgh and his country.
The 28-year-old has made 58 Test appearances for Scotland since breaking into the team in 2002 and he assumed the captaincy in 2008 during the RBS Six Nations.
His leadership skills for Edinburgh have been equally impressive and in 2009 he helped steer the Scottish club to their highest ever Magners League finish.
Blair has an eye for a gap and also provides quick, accurate ball. He is strong in the tackle and his bravery will be much-needed against the Boks.