England centre Jamie Noon has been ruled out of the remainder of the World Cup with a knee ligament injury.
Noon's injury could keep him out of action for up to six weeks
The Newcastle back is set to return home, but no decision has yet been made about a possible replacement.
England hope Jason Robinson will play still be able to play a part in the tournament, despite a hamstring strain.
The defending champions have put back their team announcement for the match against Samoa on 22 September from Monday to Tuesday.
Team doctor Simon Kemp says fly-halves Jonny Wilkinson (ankle) and Olly Barkley (hip) should be fit for the match with Samoa, who will go into the game on the back of a shock defeat by Tonga.
Noon and Robinson were both injured in England's 36-0 defeat by South Africa on Friday and had scans on their respective injuries on Saturday.
Kemp diagnosed Noon's injury as a grade two strain to a ligament in his left knee.
He said: "Arrangements are in place for him to return to Newcastle for ongoing rehabilitation. With injuries of this type a player typically won't return before six weeks, but he won't need surgery."
Noon described the moment he sustained the injury, and reflected on his bad luck.
"I am getting used to the slow realisation that my dream of playing in the Rugby World Cup is over, but what is hardest is that I have only been here for two weeks and played just two games," he said.
"However, I also know that I will be home soon and I will be there for my daughter's first birthday, so I have been thinking about that as well.
"I was running down the blindside on the right hand side of the pitch with a few minutes to go in the second half.
"I bounced off a couple of bodies and I had the ball when another player landed on my leg. I felt my knee pop, so I knew it had gone.
"The scan I had yesterday afternoon just confirmed how long I would be out for."
Robinson was injured as he tried to make an outside break
Noon's Newcastle colleague Toby Flood will be the favourite to replace him in the 30-man squad as England head into a critical Pool A clash with Samoa in Nantes on Saturday.
Robinson suffered a strain to his left hamstring, but he will remain with the squad to have further treatment and there is a chance he could be involved in future games.
Kemp said: "Although he pulled up pretty dramatically in the game, the location and signs of the strain lead us to believe Jason has every chance of playing a further part in the tournament.
"We are confident he might make a much quicker return than at first thought."
Regarding Wilkinson and Barkley, Kemp added: "They are continuing to make good progress and we have always anticipated that they would be available for selection for this week."