Captain Alun Wyn Jones and back-row pair Ross Moriarty and Taulupe Faletau have been ruled out of Wales' autumn series.
Jones and Moriarty were forced off in the first half of the 54-16 defeat against New Zealand and now require shoulder operations.
Number eight Faletau has been released from the squad due to an ankle problem.
Cardiff flanker Shane Lewis-Hughes and uncapped Ospreys lock Rhys Davies have been called into the squad.
Wales face South Africa on Saturday before games against Fiji and Australia.
No time frame has been set for Jones or Moriarty's return, but the Welsh Rugby Union (WRU) described it as a "number of months" meaning they will be major doubts to play any part in the 2022 Six Nations.
World-record cap holder Jones, 36, played his 149th international for Wales last Saturday, having also featured in 12 Tests for the British and Irish Lions.
He suffered his injury while trying to tackle New Zealand full-back Jordie Barrett in the 18th minute.
It was the same shoulder he injured during the opening Lions tour match against Japan before he made a startling recovery to travel to South Africa and start all three Tests.
Jones has signed a contract with Ospreys and Wales until the end of the 2021-22 season.
Moriarty, 27, was replaced just before half-time following a tackle by Nepo Laulala and flanker Ethan Blackadder, with Laulala yellow-carded for not wrapping his arm in the manoeuvre.
After returning from the Lions tour of South Africa this summer, Bath's Faletau has struggled with an ankle problem.
It was announced today he will leave the English club at the end of the season and is set to link with Cardiff.
Faletau, 30, was unavailable for the New Zealand match because the game was organised outside World Rugby's international window with English clubs not releasing players for the fixture.
The injured trio join fellow Lions George North, Leigh Halfpenny, Josh Navidi, Justin Tipuric and Dan Lydiate in being sidelined for the autumn series.
Dragons hooker Elliot Dee has also been sidelined with a neck problem, while Ken Owens missed the All Blacks encounter with a back injury.
Cardiff centre Willis Halaholo was also ruled out of that defeat after testing positive for Covid-19, but will be out of isolation on Friday and link up with the squad.
Returning players
There was more positive news on Dan Biggar, Liam Williams and Ellis Jenkins, who were missing against New Zealand.
Scarlets full-back Williams has not played this season after having his appendix removed, while Cardiff flanker Jenkins was absent with a rib problem and Biggar limped off for Northampton.
"Liam is training, he trained yesterday and today and he's been doing other aspects of training in the last few weeks," said kicking coach Neil Jenkins.
"He's building up nicely. He's fit and available as far as I'm concerned.
"Ellis is another one who is in contention to play on Saturday.
"The New Zealand game just came a little bit too soon for Ellis as in being able to train fully. Later on last week he trained fully and has over the last few days.
"Biggs is Biggs. He'd be in contention no matter where he was in the world. He's a fantastic player and he's a big part of our squad. I have no doubt that he should be there or thereabouts on Saturday."
If Ellis Jenkins were to be involved on Saturday, it would be his first international for almost three years after he suffered a serious knee injury playing against South Africa in November 2018.
"What he's gone through is probably no-one's business," added Neil Jenkins.
"For him to get back to this level and playing regularly at a level that he's used to, he's a fantastic rugby player.
"He's incredibly intelligent in terms of what he does and if he were to play on Saturday, it would be an incredible achievement.
"It was three years ago and he was man of the match that day. Let's hope that can happen and he puts those demons to bed."
Lewis-Hughes, 24, has three Test caps to his name, having made his international debut against Scotland in October 2020.
Lock Davies, 22, was called into the summer squad but has yet to make his senior debut for Wales.