Gareth Anscombe has been ruled out of the Rugby World Cup after injuring a knee in Wales' 33-19 defeat by England.
Fly-half Anscombe, 28, suffered an anterior cruciate ligament injury and hobbled off in the first half of the World Cup warm-up at Twickenham.
No timescale has been given on his return.
His absence leaves Dan Biggar, Jarrod Evans and Rhys Patchell as the three fly-halves in Wales' extended World Cup squad.
Wales have already lost British and Irish Lions back-rower Taulupe Faletau to a collarbone problem, while Cardiff Blues scrum-half Tomas Williams is awaiting a scan on a shoulder injury.
It is a major blow for Wales with Anscombe having established himself as Warren Gatland's first choice 10 ahead of Biggar during the last year.
Biggar replaced Anscombe against England and is in pole position to be the starting fly-half at the World Cup in Japan.
With Anscombe ruled out, there are 40 players in Gatland's World Cup squad which will be reduced to the final 31-strong party at the beginning of September.
It is also a blow for Anscombe's new side Ospreys after he joined from Cardiff Blues in April 2019, with the New Zealand-born player in danger of missing most of the 2019-20 season.
In the build-up to the England game, Gatland said criticism of Wales playing four warm-ups was "fair".
Wales play England again in Cardiff on Saturday, 17 August followed by another double-header against Ireland in Cardiff on 31 August and 7 September in Dublin as they prepare for the World Cup in Japan.
Wales' Pool D campaign begins against Georgia in Tokyo on Monday, 23 September followed by games against Australia, Fiji and Uruguay.
Analysis
Former Wales fly-half and captain Jonathan Davies
It's very disappointing, mainly for Gareth Anscombe himself and the squad. That's the risk you take when you're playing these friendlies, you've got to watch out for injuries.
Taulupe Faletau is a world-class player and you want to have your best players available during the World Cup, so to lose Faletau and then Anscombe is two big players and two big blows.
They are two tremendous footballers and for me I think perhaps that's what Wales are lacking.
If they pick Dan Biggar it will affect Wales' style of play a great deal because they are different types of player. In the Six Nations Anscombe played football and then Dan came on to close the game.
Jarrod Evans and Rhys Patchell have the opportunity now to step up in training and those two are very similar to the way Anscombe plays.