Prop Duncan Jones will fly back to Wales after it was confirmed he broke his leg during the vital win over Italy on Saturday.
Jones helped set up Wales' first try against Italy before he was hurt
Jones fractured his right leg when he fell awkwardly in a tackle after 25 minutes of Wales' 27-15 win against the Azzurri.
Wales have called up Jones' Ospreys team-mate Paul James to replace him.
James, 21, will join the squad before next weekend's game against New Zealand.
Jones will leave for home later this week once the swelling around his injury has settled down.
James, who played for Wales against Romania in a World Cup warm-up game in Wrexham, will join the Welsh squad in Sydney, where they tackle tournament favourites New Zealand on Sunday.
Said coach Steve Hansen: "He played very well at loosehead in Wrexham, and we think that youth is better than experience in this case.
"He's coming from a club that's performing well and he's been performing well, so all those things are helpful."