Conor Murray was the surprise choice to replace Alun Wyn Jones as British and Irish Lions captain for the tour to South Africa.
The Lions suffered a devastating blow as Jones was ruled out of the tour after dislocating his shoulder in the 28-10 victory over Japan at Murrayfield on Saturday.
Murray is a leftfield appointment by head coach Warren Gatland but he is a veteran of two previous Lions tours and has amassed 89 caps for his country.
The 32-year-old Ireland scrum-half started against Japan and is favourite to form a half-back partnership with Dan Biggar for the Test series.
Jones departed just eight minutes into the match after being hurt during a ruck clear-out by James Moore, and although he returned to the field to be with his team-mates at the final whistle, the Lions’ worst fears had already been realised.
After the game, Gatland said: “His shoulder dislocated. We’re getting it scanned but it’s looking like we’ll have to replace him.
“It’s very disappointing. He’s been around rugby long enough but he’ll be gutted. We need to call someone in, get them PCR tested and hopefully get them on the flight tomorrow.
“The decision’s pretty much made. I was speaking to the physios and they’ve spoken to Alun Wyn. He understands the very best case scenario is that he may get back for the Tests.”