British and Irish Lions captain Alun Wyn Jones was ruled out of the tour of South Africa after suffering a dislocated shoulder in a 28-10 warm-up win over Japan at Murrayfield on Saturday.
The match in Edinburgh, the Lions' first game in Scotland and against the Brave Blossoms, was barely eight minutes old when Jones went off after being cleared out a ruck.
Afterwards, Lions coach Warren Gatland confirmed the 35-year-old Wales lock, the world's most-capped international, would miss what would have been his fourth tour with the combined side but first as captain.
The Lions are due to fly to South Africa on Sunday, with the first of three Tests against the world champion Springboks in Cape Town on July 24.
"His shoulder dislocated. We're getting it scanned but it's looking like we'll have to replace him," Lions coach Warren Gatland told reporters.
"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."
Former Wales boss Gatland now also needs to name 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.
"We're discussing a couple of names at the moment with the coaches. Also potentially who will take over as tour captain," said Gatland.
"We have a leadership group that are pretty experienced and it's not something that is urgent to be done. But we are aware of who potentially steps into that role."
There were more injury worries for the Lions when Justin Tipuric went off in the first half to be replaced by fellow Wales back-row forward Taulupe Faletau.
"Justin got a stinger in the shoulder so we're going to check to make sure on a scan that there's no nerve damage," Gatland said.
On the pitch, the Lions ran in four tries to their opponents' one in what was Japan's first international since losing to eventual winners South Africa in the 2019 Rugby World Cup quarter-finals.
- 'No one is in shock' -
Wingers Josh Adams and Duhan van der Merwe both crossed before Ireland's Robbie Henshaw and Tadhg Beirne went over, with Wales fly-half Dan Biggar converting all four tries.
But the injuries to Jones and Tipuric threatened to overshadow the result.
Nevertheless Gatland, in charge of his third successive Lions tour, insisted: "No one is in shock because if you're in shock its reflects back into the whole squad.
"If you go into a shock scenario and look as if you are panicking then it will reflect badly on us.
"It's disappointing for Alun Wyn and also for Justin Tipuric if he is not right, but we have to do it right."
Shortly after Jones left the field, Adams marked his Lions debut with a 12th-minute try after good work by Ireland centre Bundee Aki.
Minutes later fellow flyer van der Merwe went over on the blindside for a debut Lions try of his own, as he made the most of some below par defending by Japan.
The Lions, in front of a Covid-reduced crowd of 16,500, added a third try through Henshaw to lead 21-0 at half-time before Ireland team-mate Beirne, following a well-timed pass from Biggar, sprinted clear in the 49th minute.
Japan eventually got on the scoreboard just shy of the hour mark when replacement Kazuki Himeno was driven over for a try from a line-out before Yu Tamura's penalty took the Brave Blossoms into double figures.