Wales centre Jonathan Davies is set to miss the 2018 Six Nations after being ruled out for “in the region of six months” with a foot injury.
The 29-year-old British and Irish Lions back was injured in the closing stages of Saturday’s 29-21 loss to Australia.
Scarlets’ Davies needs surgery and may miss the rest of the season.
“He’s a massive loss there’s no doubt about that,” said Wales defence coach Shaun Edwards who added they are “incredibly upset” for Davies.
“His are big shoes to fill and we have a lot of work to do over the next three weeks and through the six nations because, I’m not saying he’s irreplaceable, but it’s definitely one of the positions (players) you least want to lose.”
Edwards added: “It is probably his third really big injury in the last three or four years.
“Our thoughts are obviously with him mostly and we wish him a speedy recovery.
“He’s probably one of the form, if not the form number 13 in world rugby and he’s going to take some replacing isn’t he?”
Harlequins centre Jamie Roberts was added to Wales’ autumn Test squad before the severity of Davies’ injury was confirmed, along with prop Scott Andrews.
Webb, Tipuric & Lee doing ‘some’ training
Edwards said injured trio of scrum-half Rhys Webb, flanker Justin Tipuric and prop Samson Lee are taking “some part” in training before Saturday’s match against Georgia in Cardiff (14:30 GMT).
Lee missed the defeat by Australia with an Achilles injury and Andrews is training with the squad.
Wing Steff Evans, a team-mate of Davies at Scarlets, was replaced in the second half against the Wallabies by Hallam Amos after scoring Wales’ first try.
In the immediate aftermath of the game, Wales coach Warren Gatland said: “He’s fine, he’s just got a knock on the knee.
“It wasn’t an injury replacement.
“He’s run himself into the ground and taken a couple of big hits.
“We felt it was about the right time to make a change.”