England hooker Dylan Hartley may be forced to sit out the whole QBE autumn international series with the knee injury he sustained at the weekend.
The Northampton front-rower will definitely miss the opening Test against Fiji on November 10, but England head coach Stuart Lancaster is now sweating on Hartley's progress to ascertain whether he will be available to face Australia, South Africa and New Zealand.
The 26-year-old is expected to be sidelined for up to four weeks meaning his involvement in the series now seems unlikely and Lancaster accepts it would be a big blow to lose his first-choice hooker.
"Dylan was one of our key players in the Six Nations and in South Africa, there is no doubt about it," stated the England supremo.
"He was desperate to part of a massive autumn series and to have it snatched away so close to being here is cruel for him.
"It is not unrealistic for him to get back in the mix, but it is going to take some work. A lot of things have to happen before then.
"We have got to get him some game-time for Northampton before we can pitch him into international rugby, particularly if you look at our last two games against South Africa and New Zealand."
In Hartley's absence, England will choose between the uncapped Tom Youngs and London Irish's David Paice, who won two caps off the bench in New Zealand four years ago, for the hooker's jersey this autumn.
However, Lancaster insists he has no concerns about how either will respond in the Test arena if presented with the opportunity.
"We have had other players who have been in that situation," he continued. "Tom Croft was one of our key players in the Six Nations and he wasn't available for (the tour of) South Africa but Tom Johnson took his opportunity.
"Hopefully that can happen again. One thing I would say about trusting players who haven't got that much experience is that we have always gone with our gut instinct and to date they haven't let us down.
"Youngs has been playing well. He has been given big responsibility by Leicester in the Premiership and in Europe.
"David has matured as a player. He has had his ups and downs but I spoke to him today and he is excited. He said he is ready to stake his claim."
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