Wales and Scarlets centre Jonathan Davies has been ruled out for up to six months after suffering a foot injury.
Davies sustained the injury during Wales' 29-21 loss to Australia on Saturday and will miss his country's remaining Tests against Georgia, New Zealand and South Africa.
Davies, who has 65 caps for Wales, will need surgery and will likely also be sidelined for next year's Six Nations tournament.
"Jonathan Davies will undergo surgery to his foot following the injury sustained against Australia in the Under Armour Series," a Welsh Rugby Union statement read.
"It is envisaged that recovery will be in the region of six months."
Squad Update: @JonFoxDavies will undergo surgery to his foot following the injury sustained against Australia. It is envisaged that recovery will be in the region of six months. Get well soon Jon! pic.twitter.com/VwFRPqqvxA— Welsh Rugby Union 🏉 (@WelshRugbyUnion) November 14, 2017
The 29-year-old missed the 2015 World Cup due to a knee ligament injury, but he has been in world-class form throughout this year.
Speaking to reporters on Monday, and before the full extent of Davies' injury was announced, Wales assistant coach Neil Jenkins said: "It doesn't look great.
"He is a world-class rugby player, there is no doubting that. Any team with someone like Jon involved is certainly going to miss him.
"He was outstanding in the summer for the Lions, for us and for the Scarlets at the end of the season.
"The sad thing is he's been playing incredibly well, and it was right at the end of the game as well."
Harlequins centre Jamie Roberts was called into Wales' autumn Test squad as injury cover on Monday.
Roberts, who has won 93 caps, missed out on a place in the original 36-man party announced by Gatland last month.
Injury-hit Scotland have been rocked by another trio of withdrawals ahead of their clash with world champions New Zealand at Murrayfield.
SCOTLAND vs NEW ZEALAND
Prop WP Nel (arm fracture) and lock Tim Swinson (hand) will miss the remainder of 2017, which also includes a Test against Australia on November 25, after picking up injuries in the 44-38 victory over Samoa on Saturday.
Flanker Rob Harley, who injured his knee in training last week, will also not feature again this year.
Newcastle Falcons prop Jon Welsh has been added to the squad as cover and could play his first Test in more than two years having last appeared in the 2015 Rugby World Cup quarter-final loss to Australia at Twickenham.
Winger Tommy Seymour is also in line to feature against the All Blacks after an MRI scan on his toe revealed an injury sustained against Samoa was not as bad as first feared and he should resume training this week.
Scotland went into the internationals without 10 regulars, including props Alasdair Dickinson, Allan Dell and Gordon Reid, and hookers Fraser Brown and Ross Ford.
The side has also been without influential halfback Greig Laidlaw and lock Richie Gray.
Scotland have never beaten New Zealand, with their 30 previous meetings resulting in two draws and 28 defeats.
FRANCE vs SOUTH AFRICA
No.8 Duane Vermeulen is in line to play his first Test for more than a year after being called up by beleaguered South Africa ahead of their clash with France in Paris.
Vermeulen, who plays for French Top 14 side Toulon, won the last of his 37 Test caps against Ireland in June 2016, but has been sidelined by injury for much of the time since.
He has been brought back to add muscle to the loose forwards following a record 38-3 defeat by Ireland in Dublin on Saturday.
Prop Coenie Oosthuizen will return home from the tour after lasting two minutes in the weekend defeat before sustaining knee ligament damage that will leave him sidelined for an extended period of time, South Africa Rugby said on Monday.
Lock Pieter-Steph du Toit, one of the few Springbok players to emerge from the Ireland thrashing with credit, will also miss the Test against France after he was concussed in Dublin.
The Boks also face Italy on November 25 and Wales a week later.
IRELAND vs FIJI
Ireland have added loose forwards Jordi Murphy and New Zealand-born Sean Reidy to their squad to face Fiji in Dublin.
The pair have been drafted in as replacements for Tommy O'Donnell and Dan Leavy, who were injured ahead of last weekend's 38-3 trouncing of South Africa.
Murphy won the most recent of his 17 caps in the historic 40-29 victory over New Zealand in Chicago 12 months ago, while Reidy earned his second against Japan in June.
Two other squad members, prop John Ryan (calf) and wing Keith Earls (hamstring), will return to Munster this week for rehabilitation, while flank Peter O'Mahony has received stitches on his ear and will be monitored.