Centre Cory Allen has been released from Wales' World Cup squad after suffering a hamstring injury during Sunday's Pool A victory over Uruguay.
Allen, who scored three tries in a 54-9 victory before going off injured, will be replaced by Newport Gwent Dragons' Tyler Morgan, the Welsh Rugby Union announced.
Morgan, who was part of Wales' World Cup training group but did not make the final 31-man cut last month, will link up with the squad in London on Monday.
Allen, 22, had become only the fifth Wales player in World Cup history to score a hat-trick of tries before departing the action just before half-time.
And the Cardiff Blues player now joins Leigh Halfpenny (knee) and Rhys Webb (foot) in suffering a World Cup knockout blow, while Halfpenny's squad replacement Eli Walker was then released due to a hamstring problem just a week after being called up.
Wales 54 Uruguay 9: Player ratings
Wales 54 Uruguay 9: Player ratings
1/10 Liam Williams - 3/10
Only got his hands on the ball three times and was hammered by Uruguayan tacklers twice. Limped off with a dead leg after 35 minutes to add to Warren Gatland's injury woes.
2/10 Alex Cuthbert - 4/10
Spent most of the first half in midfield desperately searching for the ball and although he managed to get his hands on it more after the break he made very few yards and never even went close to crossing over.
3/10 Cory Allen - 8/10
It was a bitter sweet World Cup debut for Allen, who was rewarded for his superb support play and dogged determination with three first-half tries. But he limped off in the second half with a leg injury.
4/10 Hallam Amos - 8/10
Amos is unlikely to get so much room to run during the rest of the tournament and he made the most of the space. Showed impressive pace and power as well as an eagerness to offload, scored one and set up another. But he is unlikely to start against England with George North and Alex Cuthbert fit.
5/10 Rhys Priestland - 7/10
Showed moments of quality - including a brilliant chip to set up the opening try - but lacked consistency and made several unforced errors. Likely to return to the bench against England and make way for Dan Biggar.
6/10 Gareth Davies - 6/10
Has big boots to fill in the absence of Rhys Webb and he looked sharp throughout. His service was swift but he was operating behind a dominant pack and didn't really test the fringe defence until late in the second half. However, he then went on to score two late tries.
7/10 Paul James - 6/10
Made light work of his amateur opposite number in the scrum before he was taken off with a calf injury.
8/10 Samson Lee - 7/10
Looked very strong in the scrum and will be central to Wales set piece in the coming weeks after recovering from a serious ankle injury. Went over for his first international try early on but taken off at half time.
9/10 Jake Ball - 7/10
Worked very hard in the loose, made a few bruising tackles and some strong carries. Rucked with real intensity and was always quick to the clear out.
10/10 James King - 5/10
Morgan, who turned 20 earlier this month, made his Test debut in the World Cup warm-up defeat at home to Ireland just over six weeks ago.
And he follows scrum-half Mike Phillips and back-row forward Ross Moriarty in linking up with the World Cup squad after originally missing out on selection.
"It's disappointing to lose Cory in this way, especially following his man-of-the-match display against Uruguay," Wales head coach Warren Gatland said on Monday.
"Tyler was part of the our extended squad and trained very well, and will link up with us in London later today."
Speaking immediately after the Uruguay encounter, Gatland said that Allen had suffered "a significant tear" in his hamstring.
But Wales' injury worries might not necessarily end with the loss of four times-capped Allen as they build towards facing fellow Pool A heavyweights England at Twickenham next Saturday
Full-back Liam Williams, playing his first game since the end of last season due to foot trouble, picked up a thigh injury against Uruguay while Paul James and Samson Lee experienced tight calf muscles, with their fellow prop Aaron Jarvis suffering rib damage.
"Liam has got a knock on the thigh and I've spoken to the medics to get an update, but they said it will take 24 hours to make an assessment," Gatland said, during his post-match press conference.
"We may have to make a tough decision in terms of the props. We only had three that could take the field, and we have to have four. We may have to make a difficult call and replace one of the props."
Wales prepared for the World Cup with gruelling training camps in Switzerland and Qatar, but Gatland added: "Sometimes you just get bad luck, and we've had that at the moment. That happens at this level.
"You can't blame the preparation on Leigh and Rhys getting injured - they're just unlucky. We are happy with how we prepared, but we've picked up a few knocks and that's sport."
Wales, fielding largely a shadow XV, scored eight tries against Uruguay - Allen's treble, two for scrum-half Gareth Davies, plus touchdowns by Lee, Hallam Amos and Justin Tipuric - while fly-half Rhys Priestland kicked seven conversions.
But the England showdown will be light years away from Wales' opening-game stroll in terms of intensity, and Gatland said: "It will be a mental and physical battle, and we have to prepare for that.
"It is going to be tough with the crowd and the atmosphere."