Jonathan Joseph (AP)
Bagshot - England are waiting on the fitness of centre Jonathan Joseph and back-row forward Ben Morgan as they prepare for their crunch World Cup match against Wales at Twickenham on Saturday.
Joseph suffered a blow to his chest during tournament hosts England's 35-11 opening win over Fiji at Twickenham last week, while Morgan is trying to overcome a knee injury.
England are due to announce their team to play Wales on Thursday.
"Jonathan has a bit of a knock, nothing too serious and our medical staff are working extremely hard behind closed doors to get him fit for selection," England backs coach Andy Farrell told reporters at the squad's training base in Bagshot, south-west of London, on Tuesday.
"We will give him every chance to put an England shirt on this weekend.
"It's something and nothing. He has got a knock on his chest. If he is fit for this weekend, we will know by tomorrow (Wednesday) internally. If he is not fit it will not be more than a week anyway probably.
"Ben has a little bang on his knee that isn't serious at all. There are still a couple more knocks, people who are not serious. We'll leave them unnamed.
"Some guys will train today, some guys won't train today. We'll see what happens over the course of today. We don't need to rush.
"We need to take our time and give everyone the best possible chance of being fit. People have got bangs and long-term injuries who need a couple more days."
The 24-year-old Joseph, with five tries in his 14 Tests, has become England's main attacking threat in midfield and it would be a blow to England were he ruled out of the match against injury-hit Wales, who beat Uruguay 54-9 in their World Cup opener in Cardiff on Sunday.
If Joseph is sidelined, England could bring in rugby league convert Sam Burgess to partner Brad Barritt in midfield or opt for the guile of Henry Slade instead.
Playing Owen Farrell, a Saracens team-mate of Barritt's and Andy Farrell's son, at inside centre is also an option if England want to field a combination that has had game time together.
The situation in the back-row appears to be more straightforward, with Billy Vunipola, who impressed as a replacement against Fiji, likely to start at No 8 if Morgan is ruled out, with James Haskell coming on to the bench.
England and Wales have been drawn in a so-called 'Pool of Death' also featuring two-time champions Australia, with at least one of rugby union's major nations set to miss out on a quarter-final place as only the top two teams from each of the four groups go through to the last eight.