England loose forward Brad Shields faces a race against time to be fit for the World Cup after being ruled out for up to six weeks by his foot injury.
Shields last week returned home from England's warm weather training camp in Treviso after sustaining ligament damage and could miss all four preparation Tests, starting with Wales at Twickenham on Sunday week.
Eddie Jones will ideally make a call on his fitness before August 12 when he names his 31-man squad for Japan 2019, but with the tournament opener against Tonga not taking place until September 22 there is still scope for his inclusion.
A fit Shields would be destined for World Cup selection, but with Mako Vunipola, George Kruis and Jack Nowell also in various stages of rehabilitation, the squad would be in danger of carrying an escalating number of injured players.
"Brad's got a tear in the lower foot. It's always a little bit niggly, but it's four to six weeks for him," assistant coach John Mitchell said.
"If you've had a tear under the base of your foot it becomes very noticeable. He's generally a great player in the way he endures pain but on this particular occasion it became a little too acute and he was sensible enough to pull up in training and go and get it checked.
"Obviously we've got a deadline and that's important, but Eddie will decide on who's right and who's not right. There's plenty of time to go."
Mitchell was able to deliver a positive update on Kruis, however, with the Saracens lock making a return to training this week having undergone ankle surgery.
Vunipola, a certainty for inclusion in the 31, is making encouraging progress in his recovery from a hamstring complaint but England have yet to set a date for his comeback.
"George has been fantastic and the medical team have done a great job on his progressive return and he's back in training, full of enthusiasm and looking great," Mitchell said.
"Mako's progressing nicely so we should see him back at some point in August."
England are awaiting an update on Nowell, who returned home on Monday for a routine surgical review having gone under the knife to repair ankle damage.
One player with seemingly little chance of making the 31 picked in a fortnight is Danny Cipriani, who was omitted from the squad training at the 12-day 'heat camp' in north-east Italy that ends on Friday.
Cipriani's award-winning season failed to convince Jones that he should be selected for the global showpiece, but Mitchell insists that misfortune suffered by a rival could present an opportunity.
"We're going to need everyone. It doesn't matter whether you're in now or you're out preparing - the thing is that you need to be ready. Danny is no different," the defence coach said.
"We have some really good players in the squad and some really good players out. If you look at the history of recent World Cups, some positions have gone four or five deep on some occasions.
"Ultimately everyone has to be ready because it is a long way between then and finishing the World Cup."