In a major blow to England's chances of overturning their perilous position in Pool A of the 2015 Rugby World Cup, injury has ruled Billy Vunipola out for the remainder of the competition.
Vunipola left the field after picking up the injury in the defeat against Wales, and it has been confirmed that the knee ligament strain will end his tournament.
His place in the 31-man squad goes to Nick Easter, who will be appearing at his third World Cup if he takes to the field.
The injury is another blow for Stuart Lancaster, whose side are know in knockout mode with two games remaining in the pool stage after the shocking defeat on Saturday.
Big loss for England
With England's other No.8 in the squad Ben Morgan struggling for fitness, the injury to Vunipola is one which England could not afford.
Over the past few years, the Saracen has become an integral part of the squad, and gives Lancaster's side a lot of go-forward with his freakish brawn.
Lancaster said on the injury news, "It’s so unfortunate for Billy.
"He has worked really hard and committed everything to the last three months but he is a young man with a bright future."
During Saturday's defeat, Vunipola was outplaying his opposite number Toby Faletau until the injury flared, with the Welsh No.8 becoming much more of a factor in the game once England had made the enforced substitution.
Easter will make 'big contribution'
Vunipola's replacement in the squad, Nick Easter, may be the kind of experienced player England need with their backs against the wall.
Starting with the game against Australia on Saturday, Easter and his teammates must win five straight games for World Cup glory, which seems a long way away after the deflating defeat they have recently suffered.
Talking about Easter's call-up, Lancaster said, "Nick was unlucky to miss out on final selection. He is a specialist No 8 and an experienced player. We know he will make a big contribution."
The Harlequins veteran will bring more dynamism to the back-row if he is selected, as well as an excellent offloading game.
Elsewhere in the squad, England are still sweating over the fitness of Courtney Lawes, Ben Youngs and Jonathan Joseph ahead of the crunch match against the Wallabies on Saturday.
Irish and Scots also have injury concerns
As well as the obvious troubles Welsh players are having with injuries, the other home nations are also fearing major losses to their squad.
Ireland's Rob Kearney has suffered a gluteal strain which saw him play just ten minutes in Sunday's win over Romania, with a scan in the pipeline to determine the extent of the injury.
For Scotland, Grant Gilchrist has been ruled out of the tournament aftr picking up a groin strain in his country's win over USA, whilst fly-half Finn Russell is a doubt for the team's next pool game after suffering an ankle injury.