Centre Jonathan Joseph is a doubt for England's key World Cup clash with Wales on Saturday due to a chest injury.
England backs coach Andy Farrell revealed that Joseph's fitness would be determined one way or another by Wednesday.
"JJ has a bit of a knock, nothing too serious and we're working hard to get him fit," Farrell said at an England press conference at the team base in Surrey ahead of Saturday's Pool A encounter at Twickenham.
"We'll give JJ every chance to prove his fitness. We'll know if he's fit tomorrow. If he's not, then it's only a week long injury."
Farrell also revealed that No8 Ben Morgan has a bang on the knee but stressed that the injury "isn't serious at all".
Morgan did not train with England on Monday.
Source: PA