Warren Gatland admits losing Liam Williams is "undoubtedly a big loss" after he was ruled out of Wales' World Cup campaign.
The full-back will miss Sunday's semi-final against South Africa in Yokohama, as well as either the final or third and fourth place play-off next week.
Williams suffered an ankle injury following an accidental collision during training, meaning Leigh Halfpenny will wear the No 15 shirt against the Springboks, although Gatland was boosted by the return of centre Jonathan Davies after a knee injury.
"He [Williams] is undoubtedly a big loss from an attacking perspective, and what he has achieved in the game in the last year or so," said Wales head coach Gatland.
"But bringing in the experience of someone like Leigh Halfpenny gives us a different element. He is defensively probably the best full-back in the world in terms of his aerial game and coverage defensively.
"We had a long debate about whether we started Leigh in the first place and potentially move Liam to the wing. There was a long discussion about that, so Leigh was probably unlucky he was not in the team in the first place
"We are disappointed for a world-class player like Liam, but we are happy bringing in someone with the experience of Leigh.
"It is a change, but we don't think that we are weakening the side in any way with the changes we have made."
British and Irish Lions Test player Williams had been in line for a remarkable individual grand slam this year.
Aside from chasing World Cup success, he helped Wales land the Six Nations title in March, then played a crucial role as Saracens won the Champions Cup and Premiership.
The experienced Halfpenny has made one start in the tournament - in the 35-13 final pool stage match against Uruguay - and came on as a replacement against Georgia.
Davies replaces Owen Watkin and will line up alongside Hadleigh Parkes in midfield, while No 8 Ross Moriarty takes over from Josh Navidi, who suffered a hamstring injury in the France game, and had already been ruled out of the remainder of the tournament.
Gatland added: "He [Davies] has come through training this week. He was very close last week and he made a decision last week to rule himself out for the betterment of the team."