The British and Irish Lions suffered a major setback ahead of their tour of South Africa when captain Alun Wyn Jones was ruled out of the trip after suffering a shoulder injury in Saturday's warm-up match against Japan in Edinburgh.
Veteran lock Jones, 35, went off just eight minutes into a 28-10 win over Japan at Murrayfield, a curtain-raiser for an eight-game tour of South Africa that culminates with three Tests against the world champion Springboks.
"He's dislocated his shoulder," said Lions head coach Warren Gatland, with Jones appearing to suffer the injury when he was cleared out at a ruck.
"Prognosis is best case scenario is he might be okay for the first Test (at Cape Town on July 24).
"However, we've had a chat and it looks like we're going to have to replace him. It's devastating news."
The Lions are due to leave for South Africa on Sunday, with former Wales boss Gatland now having to name both a replacement and a new captain.
Wales hooker Ken Owens, who led the side initially when Jones left the field at Murrayfield, as well as England captain Owen Farrell and Red Rose team-mate Maro Itoje are among the candidates to take over the role.
This was set to be Jones' fourth Lions tour following a 2009 series loss in South Africa, the victorious 2013 trip to Australia and the drawn 2017 campaign against New Zealand.
"It's very disappointing. He's been around rugby long enough but he'll be gutted," Gatland said.
"We need to call someone in, get them PCR tested and hopefully get them on the flight tomorrow," added the New Zealander, in charge of the Lions for third successive tour.
The Lions' first game in South Africa is against the Emirates Lions in Johannesburg on July 3.